{"url_path":"/sec/nfbk/proxy/2026-05-21/000119312526234468","section_key":"body","section_title":"DEFM14A body","topic":"sec","document":{"doc_type":"DEFM14A","doc_date":"2026-05-21","source_url":"https://www.sec.gov/Archives/edgar/data/1493225/0001193125-26-234468-index.html","accession_number":"0001193125-26-234468","cik":"0001493225","ticker":"NFBK","issuer_name":"Northfield Bancorp, Inc.","edgar_url":"https://www.sec.gov/Archives/edgar/data/1493225/0001193125-26-234468-index.html","primary_entity_key":"0001493225","primary_entity_name":"Northfield Bancorp, Inc."},"word_count":29094,"has_tables":true,"body_markdown":"DEFM14A\n1\nd73323ddefm14a.htm\nDEFM14A\n\nDEFM14A\n\n##### Table of Contents\n\n**UNITED STATES**\n\n**SECURITIES AND EXCHANGE COMMISSION**\n\n**Washington, D.C. 20549**\n\n**SCHEDULE 14A INFORMATION**\n\n**Proxy Statement Pursuant to Section 14(a) of the**\n\n**Securities Exchange Act of 1934**\n\n**(Amendment No. ___)**\n\nFiled by the Registrant ☒\n\nFiled by a Party other\nthan the Registrant ☐\n\nCheck the appropriate box:\n\n☐\n\nPreliminary Proxy Statement\n\n****☐********\n\n**Confidential, for Use of the Commission Only (as permitted by\nRule 14a-6(e)(2))**\n\n☒\n\nDefinitive Proxy Statement\n\n☐\n\nDefinitive Additional Materials\n\n☐\n\nSoliciting Material pursuant to §240.14a-12\n\n**NORTHFIELD BANCORP, INC.**\n\n**(Name of Registrant as Specified in Its Charter)**\n\n**(Name of Person(s) Filing Proxy Statement, if other than the Registrant)**\n\nPayment of Filing Fee (Check the appropriate box):\n\n☒\n\nNo fee required.\n\n☐\n\nFee paid previously with preliminary materials.\n\n☐\n\nFee computed on table in exhibit required by Item 25(b) per Exchange Act\nRules 14a-6(i)(1) and 0-11.\n\n##### Table of Contents\n\n**PROSPECTUS OF COLUMBIA FINANCIAL, INC. (A MARYLAND CORPORATION)**\n\n**JOINT PROXY STATEMENT OF COLUMBIA FINANCIAL, INC. (A DELAWARE CORPORATION)**\n\n**AND NORTHFIELD BANCORP, INC.**\n\n**PROXY VOTE — YOUR VOTE IS VERY IMPORTANT**\n\nOn behalf of the boards of directors of Columbia Financial, Inc., a Delaware corporation (“Columbia Financial”), and Northfield\nBancorp, Inc., a Delaware corporation (“Northfield Bancorp”), we are pleased to enclose the accompanying joint proxy statement/prospectus relating to, among other matters, (i) the proposed conversion of Columbia Financial from the\npartially public mutual holding company form of organization to the fully public stock holding company structure (the “Conversion”) and (ii) the proposed acquisition of Northfield Bancorp by Columbia Financial, Inc., a newly formed\nMaryland corporation (“Columbia Financial, Inc.”) that will become the parent holding company of Columbia Bank upon the completion of the Conversion. We are requesting that you take certain actions as a holder of Columbia Financial\ncommon stock or a holder of Northfield Bancorp common stock.\n\nColumbia Financial is converting from the mutual holding company structure\nto the fully public ownership structure. Currently, Columbia Bank is a wholly owned subsidiary of Columbia Financial, and Columbia Bank MHC owns 73.1% of Columbia Financial’s common stock. The remaining 26.9% of Columbia Financial’s\ncommon stock is owned by public stockholders. As a result of the Conversion, Columbia Bank’s newly formed company, Columbia Financial, Inc., a Maryland corporation, will become the parent holding company of Columbia Bank. Each share of\nColumbia Financial common stock owned by the public will be exchanged for between 1.8729 and 2.5340 shares of common stock of Columbia Financial, Inc. so that Columbia Financial’s existing public stockholders will own approximately the\nsame percentage of Columbia Financial, Inc. common stock as they owned of Columbia Financial’s common stock immediately before the Conversion.\n\nConcurrently with the exchange offer, Columbia Financial, Inc. is offering up to 192,625,000 shares of common stock for sale on a best efforts\nbasis, subject to certain conditions. Columbia Financial, Inc. must sell a minimum of 142,375,000 shares to complete the offering. All shares are offered at a price of $10.00 per share. The shares Columbia Financial, Inc. is offering represent the\n73.1% ownership interest in Columbia Financial now owned by Columbia Bank MHC. Columbia Financial, Inc. is offering the shares of common stock in a “subscription offering” to eligible depositors and certain borrowers of Columbia Bank.\nShares of common stock not purchased in the subscription offering may be offered for sale to the general public in a “community offering,” with a preference given to Columbia Bank’s local communities and the stockholders of\nColumbia Financial. Columbia Financial, Inc. may also offer for sale shares of common stock not purchased in the subscription offering or the community offering in a firm commitment underwritten offering.\n\nColumbia Financial, Inc. must sell a minimum of 142,375,000 shares to complete the offering. If subscriptions totaling at least 142,375,000\nshares are not received in the subscription offering, then unsubscribed subscription offering shares may be issued to stockholders of Northfield Bancorp as merger consideration, provided that the total number of such unsubscribed shares issued to\nNorthfield Bancorp stockholders is less than 50% of Columbia Financial, Inc.’s outstanding common stock immediately after the completion of the merger of Northfield Bancorp with and into Columbia Financial, Inc. Unsubscribed shares in the\nsubscription offering may only be issued as merger consideration to Northfield Bancorp stockholders to achieve the minimum of the offering range.\n\nImmediately after the Conversion is completed, Northfield Bancorp will merge with and into Columbia Financial, Inc., pursuant to the terms of\nan Agreement and Plan of Merger, dated as of January 31, 2026, by and among Columbia Financial, Columbia Financial, Inc., Columbia Bank MHC and Northfield Bancorp (the “Merger Agreement”). Under the Merger Agreement, Northfield\nBancorp will merge with and into Columbia Financial, Inc., with Columbia Financial, Inc. continuing as the surviving corporation (the “Merger”). Immediately following the Merger, Northfield Bank, the wholly owned subsidiary of Northfield\nBancorp, will merge with and into Columbia Bank, the wholly owned subsidiary of Columbia Financial, Inc., with Columbia Bank continuing as the surviving institution (the “Bank Merger”).\n\n##### Table of Contents\n\nIf the Merger is completed, each share of Northfield Bancorp’s common stock, par value\n$0.01 per share, issued and outstanding immediately prior to the effective time of the Merger, will be converted, at the election of the holder, into the right to receive either shares of Columbia Financial, Inc. common stock or cash, as follows:\n(i) if the final independent valuation of Columbia Financial, Inc., immediately prior to the completion of the Conversion (the “Final Independent Valuation”), is less than $2.3 billion, 1.425 shares of Columbia Financial, Inc.\ncommon stock (the “Merger Exchange Ratio”) or $14.25 in cash (the “Per Share Cash Consideration”); (ii) if the Final Independent Valuation is equal to or greater than $2.3 billion and less than $2.6 billion, the\nMerger Exchange Ratio will be increased to 1.450 shares of Columbia Financial, Inc. common stock and the Per Share Cash Consideration will be increased to $14.50; or (iii) if the Final Independent Valuation is greater than $2.6 billion,\nthe Merger Exchange Ratio will be increased to 1.465 shares of Columbia Financial, Inc. and the Per Share Cash Consideration will be increased to $14.65. The “Final Independent Valuation” is also sometimes referred to herein as the\n“appraised full conversion value.” No more than 30% of the shares of Northfield Bancorp common stock issued and outstanding as of the effective time of the Merger (excluding shares of Northfield Bancorp common stock to be canceled as\nprovided the Merger Agreement) will be converted into the aggregate cash consideration. As of the date of this document, the current appraised full conversion value of Columbia Financial, Inc. is $2.291 billion at the midpoint of the offering\nrange.\n\nThe completion of the Merger is subject to the completion of the Conversion and the satisfaction of other closing conditions.\nHowever, the completion of the Conversion is not contingent on the completion of the Merger. In the event that the Merger Agreement is terminated, Columbia Financial may determine to terminate the Conversion or delay the Conversion. If Columbia\nFinancial, Inc. determines to delay the Conversion, the timing and manner of the Conversion would be subject to significant modification and subscribers would have the right to modify or rescind their purchase orders.\n\nThe common stock of Columbia Financial is listed on the Nasdaq Global Select Market under the symbol “CLBK.” The common stock of\nNorthfield Bancorp is listed on the Nasdaq Global Select Market under the symbol “NFBK.” Following the completion of the Conversion, the common stock of Columbia Financial, Inc. is expected to be listed on the Nasdaq Global Select Market\nunder the symbol “CLBK.”\n\nBased on the number of shares of Northfield Bancorp common stock outstanding and reserved for\nissuance as of April 27, 2026, Columbia Financial, Inc. expects to issue approximately 41,800,140 shares of Columbia Financial, Inc. common stock in the Merger, assuming the Final Independent Valuation is $2.291 billion (the amount of\nthe current independent valuation as of the date of this document) and 30% of the aggregate merger consideration consists of cash. Following the completion of the Merger, under such circumstances, former holders of Northfield Bancorp common stock\nwill own approximately 15.43% and existing holders of Columbia Financial, Inc. common stock (after giving effect to the Conversion) will own approximately 84.57% of the common stock of the surviving corporation at the midpoint of the offering range.\n\nColumbia Financial will hold a virtual annual meeting of its stockholders (the “Columbia Financial Annual Meeting”) on\nJune 25, 2026 at www.virtualshareholdermeeting.com/CLBK2026 at 10:00 a.m., Eastern Time. At the Columbia Financial Annual Meeting, in addition to other business, Columbia Financial will ask its stockholders to approve (i) the Conversion,\n(ii) the Merger Agreement, (iii) an informational proposal regarding a provision in Columbia Financial, Inc.’s articles of incorporation requiring a super-majority vote to approve certain amendments to Columbia Financial,\nInc.’s articles of incorporation, (iv) an informational proposal regarding approval of a provision in Columbia Financial, Inc.’s articles of incorporation limiting the voting rights of shares beneficially owned in excess of 10% of\nColumbia Financial, Inc.’s outstanding voting stock, (v) the election of directors; (vi) the ratification of KPMG LLP as Columbia Financial’s independent registered public accounting firm for fiscal 2026; (vii) an advisory vote\non the compensation of Columbia Financial’s named executive officers; (viii) an advisory vote on the frequency of the vote on the compensation of Columbia Financial’s named executive officers; and (ix) the adjournment of the\nColumbia Financial Annual Meeting, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the Columbia Financial Annual Meeting to approve the Conversion or the Merger. The approval of the Conversion by Columbia\nFinancial’s stockholders is required to complete the Merger.\n\nNorthfield Bancorp will hold a virtual special meeting of its\nstockholders (the “Northfield Bancorp Special Meeting”) on June 25, 2026 at www.virtualshareholdermeeting.com/NFBK2026SM at 9:00 a.m., Eastern Time. At the Northfield Bancorp Special Meeting, in addition to other business,\nNorthfield Bancorp will ask its stockholders to approve (i) the Merger Agreement; (ii) a proposal to approve, on a non-binding advisory basis, the compensation that may become payable to the named\nexecutive officers of Northfield Bancorp in connection with the Merger; and (iii) the adjournment of the Northfield Bancorp Special Meeting, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the\nNorthfield Bancorp Special Meeting to approve the Merger.\n\nInformation about the Columbia Financial Annual Meeting, the Northfield Bancorp\nSpecial Meeting, the Conversion and the Merger is contained in the accompanying Joint Proxy Statement/Prospectus.\n\n**Each of the boards\nof directors of Columbia Financial and Northfield Bancorp unanimously recommends that holders of Columbia Financial common stock and Northfield Bancorp common stock vote “FOR” each of the proposals to be considered at the respective\nstockholder meetings.**\n\n##### Table of Contents\n\nThe accompanying Joint Proxy Statement/Prospectus provides you with detailed information\nabout the Conversion, the Merger Agreement and the Merger. It also contains or references information about Columbia Financial, Columbia Financial, Inc., Northfield Bancorp and certain related matters. You are encouraged to read the accompanying\nJoint Proxy Statement/Prospectus carefully.** In particular, you should read the section entitled “****Risk Factors****” beginning on page********35******** for a discussion of the risks you should\nconsider in evaluating the Conversion and the Merger and how they will affect you. You can also obtain information about Columbia Financial, Columbia Financial, Inc. and Northfield Bancorp from documents that have been filed with the Securities and\nExchange Commission that are incorporated into this Joint Proxy Statement/Prospectus by reference.**\n\nWe look forward to your\nparticipation in the annual meeting and the special meeting and we appreciate your continued support.\n\nThomas J. Kemly\n\nPresident and Chief Executive Officer\n\nColumbia Financial, Inc.\n\nSteven M. Klein\n\nChairman of the\nBoard,\n\nPresident and Chief Executive Officer\n\nNorthfield\nBancorp, Inc.\n\n**The securities of Columbia Financial, Inc. to be issued in the Conversion and Merger are not deposits or\nsavings accounts or other obligations of any bank or savings association subsidiary of Columbia Financial, Columbia Financial, Inc. or Northfield Bancorp and are not insured by the Federal Deposit Insurance Corporation or any other governmental\nagency**.\n\n**Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved the\nConversion or Merger described in this document or the Columbia Financial, Inc. securities to be issued in connection with the Conversion or Merger or passed upon the adequacy or accuracy of this document. Any representation to the contrary is a\ncriminal offense**.\n\nThe accompanying Joint Proxy Statement/Prospectus is dated May 11, 2026, and it is first being mailed or\notherwise delivered to stockholders of Columbia Financial and Northfield Bancorp on or about May 21, 2026.\n\n##### Table of Contents\n\n**ABOUT THIS DOCUMENT**\n\nThis Joint Proxy Statement/Prospectus, which we also refer to as “this document,” forms part of a registration statement on Form S-4 (Registration Statement No. 333-294104) filed with the Securities and Exchange Commission (the “SEC”) by Columbia Financial, Inc., and constitutes a\nprospectus of Columbia Financial, Inc. under the Securities Act of 1933, as amended (the “Securities Act”), with respect to the shares of Columbia Financial, Inc. securities to be issued to Northfield Bancorp stockholders, as required by\nthe Merger Agreement. This document also constitutes a proxy statement for Columbia Financial and Northfield Bancorp. In addition, it constitutes a notice of meeting with respect to the annual meeting of stockholders of Columbia Financial and the\nspecial meeting of stockholders of Northfield Bancorp.\n\nYou should rely only on the information contained in this document. No one has\nbeen authorized to provide you with information that is different from the information contained in this document. This document is dated as of May 11, 2026. You should not assume that the information contained in this document is accurate as\nof any date other than that date. Neither the mailing of this document to either Columbia Financial stockholders or Northfield Bancorp stockholders nor the issuance by Columbia Financial, Inc. of its common stock in connection with the Conversion or\nthe Merger will create any implication to the contrary.\n\nThis document does not constitute an offer to sell, or a solicitation of an offer\nto buy, any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Information contained in this document regarding Columbia\nFinancial, Inc. and Columbia Financial has been provided by Columbia Financial, Inc. and Columbia Financial, respectively, and information contained in this document regarding Northfield Bancorp has been provided by Northfield Bancorp.\n\n##### Table of Contents\n\n**COLUMBIA FINANCIAL, INC.**\n\n**19-01 Route 208 North**\n\n**Fair Lawn, New Jersey 07410**\n\n**(800) 522-4167**\n\n**Notice of Annual Meeting of Stockholders to be held on June 25, 2026**\n\nTo the Stockholders of Columbia Financial, Inc.:\n\nColumbia Financial, Inc., a Delaware corporation (“Columbia Financial”), will hold a virtual annual meeting of stockholders (the\n“Columbia Financial Annual Meeting”) on June 25, 2026 at www.virtualshareholdermeeting.com/CLBK2026. The meeting will begin at 10:00 a.m., Eastern time. At the Columbia Financial Annual Meeting, stockholders of Columbia Financial\nwill consider and act on the following matters:\n\n(1)\n\nThe approval of a plan of conversion and reorganization (the “Plan of Conversion”) pursuant to\nwhich: (A) Columbia Bank MHC, which currently owns 73.1% of the common stock of Columbia Financial, will merge with and into Columbia Financial, with Columbia Financial being the surviving entity; (B) Columbia Financial will merge with and\ninto Columbia Financial, Inc., a Maryland corporation (“Columbia Financial, Inc.”), which was recently formed to be the holding company for Columbia Bank, with Columbia Financial, Inc. being the surviving entity; (C) the outstanding\nshares of Columbia Financial, other than those held by Columbia Bank MHC, will be converted into shares of common stock of Columbia Financial, Inc.; and (D) Columbia Financial, Inc. will offer shares of its common stock for sale in a\nsubscription offering and, if necessary in a community offering and/or syndicated offering (the “Columbia Conversion Proposal”).\n\n(2)\n\nThe approval of the Agreement and Plan of Merger, dated as of January 31, 2026, by and among Columbia\nFinancial, Inc. (a Delaware corporation), Columbia Financial, Inc. (a Maryland corporation), Columbia Bank MHC and Northfield Bancorp, Inc. (the “Merger Agreement”) and the transactions contemplated thereby, including the issuance of\nshares of Columbia Financial, Inc. common stock as merger consideration (the “Columbia Merger Proposal”).\n\n(3)\n\nThe approval of an informational proposal regarding approval of a provision in Columbia Financial, Inc.’s\narticles of incorporation (the “articles of incorporation”) requiring a super-majority vote to approve certain amendments to Columbia Financial, Inc.’s articles of incorporation (the “Columbia Super-Majority Proposal”).\n\n(4)\n\nThe approval of an informational proposal regarding approval of a provision in Columbia Financial, Inc.’s\narticles of incorporation to limit the voting rights of shares beneficially owned in excess of 10% of Columbia Financial, Inc.’s outstanding voting stock (the “Columbia 10% Beneficial Owner Proposal”).\n\n(5)\n\nThe election of three directors to serve for terms of three years each (the “Columbia Director Election\nProposal”).\n\n(6)\n\nThe ratification of the appointment of KPMG LLP as independent registered public accounting firm for the fiscal\nyear ending December 31, 2026 (the “Columbia Auditor Ratification Proposal”).\n\n(7)\n\nThe approval, on an advisory (non-binding) basis, of the compensation\nof Columbia Financial’s named executive officers (the “Columbia Say-on-Pay Proposal”).\n\n(8)\n\nThe approval, on an advisory (non-binding) basis, of the frequency of\nthe vote on the compensation of Columbia Financial’s named executive officers (the “Columbia Say-on-Pay Frequency Proposal”).\n\n(9)\n\nThe approval of the adjournment of the annual meeting, if necessary, to solicit additional proxies if there are\nnot sufficient votes at the time of the annual meeting to approve the Columbia Conversion Proposal or the Columbia Merger Proposal (the “Columbia Adjournment Proposal”).\n\nAll of these items are described in more detail in the accompanying Joint Proxy Statement/Prospectus and its annexes. We urge you to read\nthese materials carefully and in their entirety. The enclosed document forms a part of this notice.\n\nThe provisions of Columbia Financial,\nInc.’s articles of incorporation, which are summarized as informational proposals 3 and 4 were approved as part of the process in which the board of directors of Columbia Financial approved the Plan of Conversion. These proposals are\ninformational in nature only, because regulations of the Board of Governors of the Federal Reserve System (the “Federal Reserve Board”) governing\nmutual-to-stock conversions do not provide for votes on matters other than the Plan of Conversion. While we are asking you to vote with respect to each of the\ninformational proposals listed above, the proposed provisions for which an informational vote is requested will become effective if the stockholders of Columbia Financial approve the Plan of Conversion, regardless of whether stockholders vote to\napprove any or all of the informational proposals.\n\n**The Columbia Financial board of directors unanimously recommends that Columbia\nFinancial stockholders vote “FOR” the Columbia Conversion Proposal, “FOR” the Columbia Merger Proposal, “FOR” the Columbia Super-**\n\n##### Table of Contents\n\n**Majority Proposal, “FOR” the Columbia 10% Beneficial Owner Proposal, “FOR” the Columbia Director Election Proposal, “FOR” the Columbia Auditor Ratification\nProposal, “FOR” the Columbia Say-on-Pay Proposal, for “ONE YEAR” for the Columbia\nSay-on-Pay Frequency Proposal and “FOR” the Columbia Adjournment Proposal.**\n\nColumbia Financial stockholders of record as of the close of business on April 30, 2026 are entitled to notice of, and to vote at, the\nColumbia Financial Annual Meeting and any adjournments or postponements of the Columbia Financial Annual Meeting**.**\n\n**Your vote is\nvery important.******We cannot complete the transactions contemplated by the Plan of Conversion and the Merger Agreement unless holders of Columbia Financial common stock approve the Columbia Conversion Proposal and the Columbia Merger\nProposal. The affirmative vote of a majority of all the votes entitled to be cast at the Columbia Financial Annual Meeting by stockholders other than Columbia Bank MHC is required to approve the Columbia Conversion Proposal and the Columbia Merger\nProposal. The Columbia Super-Majority Proposal, the Columbia 10% Beneficial Owner Proposal, the Columbia Auditor Ratification Proposal, the Columbia Say-on-Pay Proposal\nand the Columbia Adjournment Proposal must each be approved by the affirmative vote of the majority of the votes cast at the Columbia Financial Annual Meeting. Directors are elected by a plurality of votes cast at the Columbia Financial Annual\nMeeting. For the Columbia Say-on-Pay Frequency Proposal, the choice of frequency that receives the highest votes will be considered the advisory vote of stockholders.\n\nEach copy of the Joint Proxy Statement/Prospectus mailed to holders of Columbia Financial common stock is accompanied by a form of proxy\ncard with instructions for voting.\n\nWhether or not you plan to attend the Columbia Financial Annual Meeting, we urge you to please\npromptly complete, sign, date and return the accompanying proxy card in the enclosed postage-paid envelope or authorize the individuals named on the accompanying proxy card to vote your shares by calling the toll-free telephone number or by using\nthe Internet as described in the instructions included with the accompanying proxy card. If your shares are held in the name of a bank, broker, trustee or other nominee, please follow the instructions on the voting instruction card furnished by such\nbank, broker, trustee or other nominee.\n\nThe Joint Proxy Statement/Prospectus of which this notice is part provides a detailed description\nof the Plan of Conversion, the Merger Agreement and the other matters to be considered at the Columbia Financial Annual Meeting. We encourage you to carefully read this Joint Proxy Statement/Prospectus (including the annexes thereto) and any other\ndocuments incorporated by reference herein in their entirety.\n\nIf you have any questions regarding the accompanying Joint Proxy\nStatement/Prospectus, please contact The Laurel Hill Advisory Group, LLC, Columbia Financial’s proxy solicitor, by calling toll-free at (888) 742-1305 and (516) 933-3100 for banks and brokers.\n\nBy Order of the Board of Directors\n\nMayra L. Rinaldi\n\n*Executive Vice President, Corporate Governance and*\n\n*Culture and Corporate Secretary*\n\nMay 11, 2026\n\n##### Table of Contents\n\n**NORTHFIELD BANCORP, INC.**\n\n**581 Main Street, Suite 810**\n\n**Woodbridge, New Jersey 07095**\n\n**(732) 499-7200**\n\n**Notice of Special Meeting of Stockholders to be held on June 25, 2026**\n\nTo the Stockholders of Northfield Bancorp, Inc.:\n\nNorthfield Bancorp, Inc., a Delaware corporation (“Northfield Bancorp”), will hold a virtual special meeting of stockholders (the\n“Northfield Bancorp Special Meeting”) on June 25, 2026. The meeting will begin at 9:00 a.m., Eastern time. You may participate in the Northfield Bancorp Special Meeting, submit questions, and vote online, until voting is closed,\nat www.virtualshareholdermeeting.com/NFBK2026SM.\n\nAt the Northfield Bancorp Special Meeting, stockholders of Northfield Bancorp will\nconsider and act on the following matters:\n\n(1)\n\nThe approval of the Agreement and Plan of Merger, dated as of January 31, 2026, by and among Columbia\nFinancial, Inc. (a Delaware corporation), Columbia Financial, Inc. (a Maryland corporation), Columbia Bank MHC and Northfield Bancorp, Inc. (the “Merger Agreement”) and the transactions contemplated thereby (the “Northfield Merger\nProposal”).\n\n(2)\n\nThe approval, on an advisory (non-binding) basis, of the compensation\nthat may become payable to the named executive officers of Northfield Bancorp in connection with the transactions contemplated by the Merger Agreement (the “Northfield Merger-Related Compensation Proposal”).\n\n(3)\n\nThe approval of the adjournment of the special meeting, if necessary, to solicit additional proxies if there\nare not sufficient votes at the time of the special meeting to approve the Northfield Merger Proposal (the “Northfield Adjournment Proposal”).\n\nAll of these items are described in more detail in the accompanying Joint Proxy Statement/Prospectus and its annexes. We urge you to read\nthese materials carefully and in their entirety. The enclosed document forms a part of this notice.\n\n**The Northfield Bancorp board of\ndirectors unanimously recommends that Northfield Bancorp stockholders vote “FOR” the Northfield Merger Proposal, “FOR” the Northfield Merger-Related Compensation Proposal and “FOR” the Northfield Adjournment\nProposal.**\n\nNorthfield Bancorp stockholders of record as of the close of business on April 27, 2026 are entitled to notice of, and\nto vote at, the Northfield Bancorp Special Meeting and any adjournments or postponements of the Northfield Bancorp Special Meeting**.**\n\n**Your vote is very important.******We cannot complete the transactions contemplated by the Merger Agreement unless holders of\nNorthfield Bancorp common stock approve the Northfield Merger Proposal. The affirmative vote of a majority of all the stock entitled to be voted at the Northfield Bancorp Special Meeting is required to approve the Northfield Merger Proposal. The\nNorthfield Merger-Related Compensation Proposal and the Northfield Adjournment Proposal must each be approved by the affirmative vote of the majority of the votes cast at the Northfield Bancorp Special Meeting.\n\nEach copy of the Joint Proxy Statement/Prospectus mailed to holders of Northfield Bancorp common stock is accompanied by a form of proxy card\nwith instructions for voting.\n\nWhether or not you plan to virtually attend the Northfield Bancorp Special Meeting, we urge you to please\npromptly complete, sign, date and return the accompanying proxy card in the enclosed postage-paid envelope or authorize the individuals named on the accompanying proxy card to vote your shares by calling the toll-free telephone number or by using\nthe Internet as described in the instructions included with the accompanying proxy card. If your shares are held in the name of a bank, broker, trustee or other nominee, please follow the instructions on the voting instruction card furnished by such\nbank, broker, trustee or other nominee.\n\nThe Joint Proxy Statement/Prospectus of which this notice is part provides a detailed description\nof the Merger Agreement and the other matters to be considered at the Northfield Bancorp Special Meeting. We encourage you to carefully read this Joint Proxy Statement/Prospectus (including the annexes thereto) and any other documents incorporated\nby reference herein in their entirety.\n\nIf you have any questions regarding the accompanying Joint Proxy Statement/Prospectus, please\ncontact Lioness Consulting LLC, Northfield Bancorp’s proxy solicitor, by calling toll-free at (833) 820-9861, or by e-mail at NFBK@lionessconsultingllc.com.\n\nBy Order of the Board of Directors\n\nSusan Aufiero-Peters, Esq.\n\n*Senior Vice President and Corporate Secretary*\n\nMay 11, 2026\n\n##### Table of Contents\n\n**ADDITIONAL INFORMATION**\n\nColumbia Financial, Columbia Financial, Inc. and Northfield Bancorp file annual, quarterly and current reports, proxy statements and other\nbusiness and financial information electronically with the SEC, as applicable. You can obtain any of the documents filed with or furnished to the SEC by Columbia Financial or Northfield Bancorp at no cost from the SEC’s website at www.sec.gov.\nYou will also be able to obtain these documents free of charge from Columbia Financial by accessing Columbia Financial’s website at www.columbiabankonline.com under the “Investor Relations” tab, or from Northfield Bancorp by\naccessing Northfield Bancorp’s website at www.enorthfield.com under the “Investor Relations” tab. See “Where You Can Find More Information” on page 335.\n\nYou also may request orally or in writing copies of these documents at no cost by contacting the appropriate company at the following\naddresses:\n\nColumbia Financial, Inc.\n\n19-01 Route 208 North\n\nFair Lawn, New Jersey 07410\n\nAttention: Corporate Secretary\n\nTelephone: (833) 550-0717\n\nNorthfield Bancorp, Inc.\n\n581 Main Street, Suite 810\n\nWoodbridge, New Jersey 07095\n\nAttention: Corporate Secretary\n\nTelephone: (732) 499-7200 (ext. 2540)\n\n**If you are a Columbia Financial stockholder or Northfield Bancorp stockholder and would like to request\ndocuments from Columbia Financial or Northfield Bancorp, please do so by June 18, 2026 to receive them before the Columbia Financial Annual Meeting or the Northfield Bancorp Special Meeting.**\n\nThe information on Columbia Financial’s and Northfield Bancorp’s websites is not part of this document. References to Columbia\nFinancial’s and Northfield Bancorp’s websites in this document are intended to serve as textual references only.\n\n##### Table of Contents\n\n**TABLE OF CONTENTS**\n\n**Page**\n\n[Questions and Answers](#toc92655_1)\n\n1\n\n[Summary](#toc92655_2)\n\n15\n\n[Risk Factors](#toc92655_3)\n\n35\n\n[Cautionary Statement About Forward-Looking Statements](#toc92655_4)\n\n55\n\n[Annual Meeting of Columbia Financial Stockholders](#toc92655_5)\n\n57\n\n[Columbia Financial Proposal No. 1: The Columbia Conversion\nProposal](#toc92655_6)\n\n61\n\n[Columbia Financial Proposal No. 2: The Columbia Merger\nProposal](#toc92655_7)\n\n62\n\n[Columbia Financial Proposal No. 3: The Columbia Super-Majority\nProposal](#toc92655_8)\n\n63\n\n[Columbia Financial Proposal No.\n4: The Columbia 10% Beneficial Owner Proposal](#toc92655_9)\n\n64\n\n[Columbia Financial Proposal No.\n5: The Columbia Director Election Proposal](#toc92655_10)\n\n65\n\n[Columbia Financial Proposal No.\n6: The Columbia Auditor Ratification Proposal](#toc92655_11)\n\n68\n\n[Columbia Financial Proposal No. 7: The Columbia Say-on-Pay Proposal](#toc92655_12)\n\n70\n\n[Columbia Financial Proposal No. 8: The Columbia Say-on-Pay Frequency Proposal](#toc92655_13)\n\n71\n\n[Columbia Financial Proposal No. 9: The Columbia Adjournment\nProposal](#toc92655_14)\n\n72\n\n[Special Meeting of Northfield Bancorp Stockholders](#toc92655_15)\n\n73\n\n[Northfield Bancorp Proposal No. 1: The Northfield Merger\nProposal](#toc92655_16)\n\n77\n\n[Northfield Bancorp Proposal No.\n2: The Northfield Merger-Related Compensation Proposal](#toc92655_17)\n\n78\n\n[Northfield Bancorp Proposal No. 3: The Northfield Adjournment\nProposal](#toc92655_18)\n\n79\n\n[Description of the Conversion](#toc92655_19)\n\n80\n\n[Description of the Merger](#toc92655_20)\n\n94\n\n[Selected Consolidated Financial and Other Data of Columbia Financial and Subsidiaries](#toc92655_21)\n\n155\n\n[Selected Consolidated Financial and Other Data of Northfield Bancorp and Subsidiaries](#toc92655_22)\n\n157\n\n[Recent Developments of Columbia Financial](#toc92655_22a)\n\n159\n\n[Recent Developments of Northfield Bancorp](#toc92655_22b)\n\n163\n\n[How Columbia Financial, Inc. Intends to Use the Proceeds from the\nOffering](#toc92655_23)\n\n168\n\n[Dividend Policy of Columbia Financial, Inc.](#toc92655_24)\n\n170\n\n[Market for the Common Stock](#toc92655_25)\n\n171\n\n[Capitalization](#toc92655_26)\n\n172\n\n[Historical and Pro Forma Regulatory Capital Compliance](#toc92655_27)\n\n174\n\n[Pro Forma Unaudited Condensed Consolidated Financial Statements Giving Effect\nto the Conversion and Proposed Merger](#toc92655_28)\n\n177\n\n[Pro Forma Data](#toc92655_29)\n\n184\n\n[Business of Columbia Financial and Columbia Bank](#toc92655_30)\n\n189\n\n[Management’s Discussion and Analysis of Financial Condition and Results\nof Operations of Columbia Financial](#toc92655_31)\n\n201\n\n[Business of Northfield Bancorp and Northfield Bank](#toc92655_32a)\n\n231\n\n[Management’s Discussion and Analysis of Financial Condition and Results\nof Operations of Northfield Bancorp](#toc92655_33a)\n\n249\n\n[Management of Columbia Financial, Inc.](#toc92655_34)\n\n267\n\n[Stock Ownership of Columbia Financial](#toc92655_35)\n\n302\n\n[Stock Ownership of Northfield Bancorp](#toc92655_36)\n\n304\n\n[Subscriptions by Executive Officers and Directors of Columbia\nFinancial](#toc92655_37)\n\n306\n\n[Regulation and Supervision](#toc92655_38)\n\n307\n\n[Comparison of Stockholders’ Rights of Columbia Financial, Inc. and Columbia\nFinancial](#toc92655_39)\n\n315\n\n[Comparison of Stockholders’ Rights of Columbia Financial, Inc. and Northfield\nBancorp](#toc92655_40)\n\n322\n\n[Restrictions on Acquisition of Columbia Financial, Inc.](#toc92655_41)\n\n329\n\n[Description of Columbia Financial, Inc. Capital Stock](#toc92655_42)\n\n333\n\n[Transfer Agent and Registrar](#toc92655_43)\n\n334\n\n[Registration Requirements](#toc92655_44)\n\n334\n\n[Legal Matters](#toc92655_45)\n\n334\n\n[Experts](#toc92655_46)\n\n334\n\n[Submission of Business Proposals and Stockholder Nominations](#toc92655_47)\n\n334\n\n##### Table of Contents\n\n**Page**\n\n[Stockholder Communications](#toc92655_48)\n\n335\n\n[Where You Can Find More Information](#toc92655_49)\n\n335\n\n[Index to Financial Statements of Columbia Financial](#toc92655_50)\n\nF-1\n\n[Index to Financial Statements of Northfield Bancorp](#toc92655_51)\n\nF-79\n\n[*Annex A*: Agreement and Plan of Merger, dated as of January 31,\n2026, by and among Columbia Financial, Inc., a Delaware corporation, Columbia Financial, Inc., a Maryland corporation, Columbia Bank MHC and Northfield Bancorp, Inc.](#toc92655_52)\n\nA-1\n\n[*Annex B*: Opinion of Keefe, Bruyette & Woods,\nInc.](#toc92655_53)\n\nB-1\n\n[*Annex C*: Opinion of Raymond James & Associates,\nInc.](#toc92655_54)\n\nC-1\n\n##### Table of Contents\n\n**QUESTIONS AND ANSWERS**\n\nThe following questions and answers are intended to address briefly some commonly asked questions regarding the annual meeting of stockholders\n(the “Columbia Financial Annual Meeting”) of Columbia Financial, Inc., a Delaware corporation (“Columbia Financial”) and the special meeting of stockholders (the “Northfield Bancorp Special Meeting”) of Northfield\nBancorp, Inc. (“Northfield Bancorp”). These questions and answers may not address all questions that may be important to you as a Columbia Financial or Northfield Bancorp stockholder. To more fully understand the Conversion, the Merger,\nthe Columbia Financial Annual Meeting and the Northfield Bancorp Special Meeting, you should read this entire Joint Proxy Statement/Prospectus, including the materials attached as annexes, as well as the documents that have been incorporated by\nreference into this Joint Proxy Statement/Prospectus.\n\n**The Proxy Vote**\n\n**Q:**\n\n**Why am I receiving this Joint Proxy Statement/Prospectus?**\n\nA:\n\nYou are receiving this Joint Proxy Statement/Prospectus because you are a stockholder of either Columbia\nFinancial or Northfield Bancorp. This Joint Proxy Statement/Prospectus relates to, among other matters, (i) the proposed conversion of Columbia Financial from the partially public mutual holding company form of organization to the fully public\nstock holding company structure (the “Conversion”) pursuant to the terms of a plan of conversion and reorganization (the “Plan of Conversion”) and (ii) the proposed acquisition of Northfield Bancorp by Columbia\nFinancial, Inc., a newly formed Maryland corporation (“Columbia Financial, Inc.”) that will become the parent holding company of Columbia Bank upon the completion of the Conversion. We are requesting that you take certain actions as a\nholder of Columbia Financial common stock or a holder of Northfield Bancorp common stock.\n\nColumbia Financial is\nconverting from the mutual holding company structure to the fully public ownership structure. Currently, Columbia Bank is a wholly owned subsidiary of Columbia Financial, and Columbia Bank MHC owns 73.1% of Columbia Financial’s common stock.\nThe remaining 26.9% of Columbia Financial’s common stock is owned by public stockholders. As a result of the Conversion, Columbia Bank’s newly formed company, Columbia Financial, Inc., a Maryland corporation, will become the parent\nholding company of Columbia Bank. Each share of Columbia Financial common stock owned by the public will be exchanged for between 1.8729 and 2.5340 shares of common stock of Columbia Financial, Inc. so that Columbia Financial’s existing public\nstockholders will own approximately the same percentage of Columbia Financial, Inc. common stock as they owned of Columbia Financial’s common stock immediately before the Conversion.\n\nConcurrently with the exchange offer, Columbia Financial, Inc. is offering up to 192,625,000 shares of common stock for sale on a best efforts\nbasis, subject to certain conditions. All shares are offered at a price of $10.00 per share. The shares Columbia Financial, Inc. is offering represent the 73.1% ownership interest in Columbia Financial now owned by Columbia Bank MHC. Columbia\nFinancial, Inc. is offering the shares of common stock in a “subscription offering” to eligible depositors and certain borrowers of Columbia Bank. Shares of common stock not purchased in the subscription offering may be offered for sale\nto the general public in a “community offering,” with a preference given to Columbia Bank’s local communities and the stockholders of Columbia Financial. Columbia Financial, Inc. may also offer for sale shares of common stock not\npurchased in the subscription offering or the community offering in a firm commitment underwritten offering.\n\nColumbia Financial, Inc. must\nsell a minimum of 142,375,000 shares to complete the offering. If subscriptions totaling at least 142,375,000 shares are not received in the subscription offering, then unsubscribed subscription offering shares may be issued to stockholders of\nNorthfield Bancorp as merger consideration, or in any other manner that facilitates the completion of the Merger, provided that the total number of such unsubscribed shares issued to Northfield Bancorp stockholders is less than 50% of Columbia\nFinancial, Inc.’s outstanding common stock immediately after the completion of the Merger. Unsubscribed shares in the subscription offering may only be issued as merger consideration to Northfield Bancorp stockholders to achieve the minimum of\nthe offering range.\n\nImmediately after the Conversion is completed, Northfield Bancorp will merge with and into Columbia Financial, Inc.,\npursuant to the terms of an Agreement and Plan of Merger, dated as of January 31, 2026, by and among Columbia Financial, Columbia Financial, Inc., Columbia Bank MHC and Northfield Bancorp (the “Merger Agreement”). Under the Merger\nAgreement, Northfield Bancorp will merge with and into Columbia Financial, Inc., with Columbia Financial, Inc. continuing as the surviving corporation (the “Merger”). Immediately following the Merger, Northfield Bank, the wholly owned\nsubsidiary of Northfield Bancorp, will merge with and into Columbia Bank, the wholly owned subsidiary of Columbia Financial, Inc., with Columbia Bank continuing as the surviving institution (the “Bank Merger”).\n\nThe completion of the Merger is subject to the completion of the Conversion and the satisfaction of other closing conditions. However, the\ncompletion of the Conversion is not contingent on the completion of the Merger. In the event\n\n1\n\n##### Table of Contents\n\nthat the Merger Agreement is terminated, Columbia Financial may determine to terminate the Conversion or delay the Conversion. If Columbia Financial, Inc. determines to delay the Conversion, the\ntiming and manner of the Conversion would be subject to significant modification and subscribers would have the right to modify or rescind their purchase orders.\n\nColumbia Financial will hold the Columbia Financial Annual Meeting on June 25, 2026 at www.virtualshareholdermeeting.com/CLBK2026 at 10:00\na.m., Eastern Time. At the Columbia Financial Annual Meeting, in addition to other business, Columbia Financial will ask its stockholders to approve (i) the Plan of Conversion (the “Columbia Conversion Proposal”), (ii) the Merger\nAgreement and the consummation of the transactions contemplated thereby, including the issuance of shares of Columbia Financial, Inc. common stock as merger consideration (the “Columbia Merger Proposal”), (iii) an informational proposal\nregarding a provision in Columbia Financial, Inc.’s articles of incorporation requiring a super-majority vote to approve certain amendments to Columbia Financial, Inc.’s articles of incorporation (the “Columbia Super-Majority\nProposal”), (iv) an informational proposal regarding approval of a provision in Columbia Financial, Inc.’s articles of incorporation limiting the voting rights of shares beneficially owned in excess of 10% of Columbia Financial,\nInc.’s outstanding voting stock (the “Columbia 10% Beneficial Owner Proposal”), (v) the election of directors (the “Columbia Director Election Proposal”), (vi) the ratification of KPMG LLP as Columbia Financial’s\nindependent registered public accounting firm for fiscal 2026 (the “Columbia Auditor Ratification Proposal”), (vii) an advisory vote on the compensation of Columbia Financial’s named executive officers (the “Columbia Say-on-Pay Proposal”), (viii) an advisory vote on the frequency of the vote on the compensation of Columbia Financial’s named executive officers (the\n“Columbia Say-on-Pay Frequency Proposal”) and (ix) the adjournment of the Columbia Financial Annual Meeting, if necessary, to solicit additional proxies\nif there are not sufficient votes at the time of the Columbia Financial Annual Meeting to approve the Plan of Conversion or the Merger Agreement (the “Columbia Adjournment Proposal”). The approval of the Plan of Conversion and the Merger\nAgreement by Columbia Financial’s stockholders is required to complete the Merger.\n\nNorthfield Bancorp will hold the Northfield\nBancorp Special Meeting on June 25, 2026 at www.virtualshareholdermeeting.com/NFBK2026SM at 9:00 a.m., Eastern Time. At the Northfield Bancorp Special Meeting, in addition to other business, Northfield Bancorp will ask its stockholders to approve\n(i) the Merger Agreement (the “Northfield Merger Proposal”); (ii) a proposal to approve, on a non-binding advisory basis, the compensation that may become payable to the named executive\nofficers of Northfield Bancorp in connection with the Merger (the “Northfield Merger-Related Compensation Proposal”); and (iii) the adjournment of the Northfield Bancorp Special Meeting, if necessary, to solicit additional proxies\nif there are not sufficient votes at the time of the Northfield Bancorp Special Meeting to approve the Merger (the “Northfield Adjournment Proposal”).\n\n**The Columbia Financial board of directors unanimously recommends that Columbia Financial stockholders vote “FOR” the Columbia\nConversion Proposal, “FOR” the Columbia Merger Proposal, “FOR” the Columbia Super-Majority Proposal, “FOR” the Columbia 10% Beneficial Owner Proposal, “FOR” the Columbia Director Election Proposal,\n“FOR” the Columbia Auditor Ratification Proposal, “FOR” the Columbia Say-on-Pay Proposal, for “ONE YEAR” for the Columbia Say-on-Pay Frequency Proposal and “FOR” the Columbia Adjournment Proposal.**\n\n**The Northfield Bancorp board of directors unanimously recommends that Northfield Bancorp stockholders vote “FOR” the Northfield\nMerger Proposal, “FOR” the Northfield Merger-Related Compensation Proposal and “FOR” the Northfield Adjournment Proposal.**\n\n**YOUR VOTE IS IMPORTANT. WE CANNOT COMPLETE THE CONVERSION AND MERGER UNLESS THE STOCKHOLDERS OF COLUMBIA FINANCIAL APPROVE THE PLAN OF\nCONVERSION AND THE MERGER AGREEMENT AND THE STOCKHOLDERS OF NORTHFIELD BANCORP APPROVE THE MERGER AGREEMENT.**\n\n**The Conversion**\n\n**Q:**\n\n**What is the Conversion and the related offering?**\n\nA:\n\nColumbia Financial is converting from a partially-public mutual holding company structure to a fully-public\nstock holding company ownership structure. Currently, Columbia Bank MHC owns 73.1% of Columbia Financial’s common stock. The remaining 26.9% of Columbia Financial’s common stock is owned by public stockholders. As a result of the\nConversion, Columbia Financial, Inc. will become the parent of Columbia Bank.\n\nShares of common stock of Columbia\nFinancial, Inc., representing the 73.1% ownership interest of Columbia Bank MHC in Columbia Financial, are being offered for sale to eligible depositors and borrowers of Columbia Bank and, possibly, to the public. At the completion of the Conversion\nand related offering, public stockholders of Columbia Financial will exchange their shares of Columbia Financial common stock for shares of common stock of Columbia Financial, Inc.\n\n2\n\n##### Table of Contents\n\nAfter the Conversion and offering are completed, Columbia Bank will be a wholly-owned\nsubsidiary of Columbia Financial, Inc., 100% of the common stock of Columbia Financial, Inc. will be owned by public stockholders, and Columbia Financial will have completed the transition from partial to fully-public ownership. As a result of the\nConversion and offering, Columbia Financial and Columbia Bank MHC will cease to exist.\n\nSee the section of this Joint Proxy\nStatement/Prospectus captioned “*Description of the Conversion*” for more information about the Conversion and offering.\n\n**Q:**\n\n**What are the reasons for the Conversion and stock offering?**\n\nA:\n\nThe primary reasons for the Conversion and offering are to (i) facilitate the acquisition of Northfield\nBancorp by Columbia Financial, Inc.; (ii) enhance stockholder returns through higher earnings and more flexible capital management strategies; (iii) strengthen Columbia Financial, Inc.’s capital position with the additional capital it\nwill raise in the offering to support its planned growth; (iv) eliminate the current limitations imposed by the mutual holding company structure on dividend payments and make it less costly for Columbia Financial, Inc. to pay dividends;\n(v) transition Columbia Financial to a more familiar and flexible organizational structure and create a more liquid and active market for shares of Columbia Financial, Inc. common stock; and (vi) facilitate future mergers and acquisitions\n(although Columbia Financial, Inc. does not currently have any understandings or agreements regarding any specific acquisition transaction other than the Merger).\n\n**Q:**\n\n**I currently own shares of Columbia Financial common stock. What will happen to my shares as a result of the\nConversion?**\n\nA:\n\nAt the completion of the Conversion, your shares of Columbia Financial common stock will be canceled and\nexchanged for shares of common stock of Columbia Financial, Inc., a newly formed Maryland corporation. The number of shares you will receive will be based on an exchange ratio (the “Conversion Exchange Ratio”), determined as of the\ncompletion of the Conversion and offering, that is intended to result in Columbia Financial’s existing public stockholders owning approximately 26.9% of Columbia Financial, Inc.’s common stock, which is the same percentage of Columbia\nFinancial common stock currently owned by existing public stockholders as adjusted to reflect the assets of Columbia Bank MHC.\n\n**Q:**\n\n**Does the Conversion Exchange Ratio depend on the market price of Columbia Financial common stock?**\n\nA:\n\nNo, the Conversion Exchange Ratio will not be based on the market price of Columbia Financial common stock.\nTherefore, changes in the price of Columbia Financial common stock between now and the completion of the Conversion and offering will not affect the calculation of the Conversion Exchange Ratio.\n\n**Q:**\n\n**How will the actual Conversion Exchange Ratio be determined?**\n\nA:\n\nBecause the purpose of the Conversion Exchange Ratio is to maintain the ownership percentage of the existing\npublic stockholders of Columbia Financial, the actual Conversion Exchange Ratio will depend on the number of shares of Columbia Financial, Inc.’s common stock sold in the offering and, therefore, cannot be determined until the completion of\nthe Conversion and offering.\n\n**Q:**\n\n**How many shares of Columbia Financial, Inc. will stockholders of Columbia Financial receive in the\nConversion exchange?**\n\nA:\n\nHolders of Columbia Financial common stock will receive between 1.8729 and 2.5340 shares of Columbia Financial,\nInc. common stock for each share of Columbia Financial common stock they own on the date of the completion of the Conversion and offering. For example, if you own 100 shares of Columbia Financial common stock, and the Conversion Exchange Ratio is\n2.2035 (at the midpoint of the offering range), you will receive 220 shares of Columbia Financial, Inc. common stock and $3.50 in cash, the value of the fractional share, based on the $10.00 per share purchase price in the offering. Stockholders who\nhold shares in street name at a brokerage firm or are held in book-entry form by Columbia Financial’s transfer agent will receive these funds in their accounts. Stockholders who hold stock certificates will receive a check in the mail.\n\n**Q:**\n\n**Should I submit my Columbia Financial stock certificates now?**\n\nA:\n\nNo. If you hold a stock certificate for Columbia Financial common stock, instructions for exchanging your\ncertificate will be sent to you after completion of the Conversion and offering. Until you submit the transmittal form and\n\n3\n\n##### Table of Contents\n\ncertificate, you will not receive your new certificate and check for cash in lieu of fractional shares, if any. If your shares are held in street name at a brokerage firm, the share exchange will\noccur automatically upon completion of the conversion and offering, without any action on your part. **Please do not send in your stock certificate until you receive a transmittal form and instructions.**\n\n**Q:**\n\n**When does Columbia Financial expect to complete the Conversion?**\n\nA:\n\nColumbia Financial expects to complete the Conversion early in the third quarter of 2026; however, there is no\nassurance as to when or if the Conversion will be completed. Prior to the consummation of the Conversion, the stockholders of Columbia Financial and the members of Columbia Bank MHC must approve the Conversion and other conditions to the\nconsummation of the Conversion must be satisfied.\n\n**Q:**\n\n**Is the completion of the Conversion contingent upon the completion of the Merger?**\n\nWhile the completion of the Merger is subject to the completion of the Conversion, and the satisfaction of other closing conditions, the\ncompletion of the Conversion is not contingent on the completion of the Merger. In the event that the Merger Agreement is terminated, Columbia Financial may determine to terminate the Conversion or delay the Conversion. If Columbia Financial\ndetermines to delay the Conversion, the timing and manner of the Conversion would be subject to significant modification and subscribers would have the right to modify or rescind their purchase orders.\n\n**Q:**\n\n**What are the material U.S. federal income tax consequences of the Conversion to Columbia Financial\nstockholders?**\n\nA:\n\nAs a general matter, for U.S. federal and state income tax purposes, the Conversion is not expected to be a\ntaxable transaction to (i) Columbia Financial, Inc., (ii) existing stockholders of Columbia Financial that receive Columbia Financial, Inc. common stock in exchange for their Columbia Financial common stock or (iii) persons who receive or\nexercise subscription rights. Existing stockholders of Columbia Financial who receive cash in lieu of a fractional share interest in Columbia Financial, Inc. are expected to recognize gain or loss equal to the difference between the cash received\nand the tax basis of the fractional share.\n\n**Q:**\n\n**Do stockholders of Columbia Financial have dissenters’ and appraisal rights in connection with the\nConversion and offering?**\n\nA:\n\nNo. Stockholders of Columbia Financial do not have dissenters’ rights in connection with the Conversion\nand offering.\n\n**Q:**\n\n**May I place an order to purchase shares in the offering, in addition to the shares I will receive in\nexchange for my shares of Columbia Financial common stock?**\n\nA:\n\nEligible depositors and borrowers of Columbia Bank have priority subscription rights allowing them to purchase\ncommon stock in the subscription offering. Shares not purchased in the subscription offering may be made available for sale to the public in a community offering and/or a firm commitment offering. If you would like to receive a prospectus and stock\norder form, please call Columbia Financial, Inc.’s Stock Information Center at (844) 265-9680 from 10:00 a.m. to 4:00 p.m., Eastern time, Monday through Friday. The Stock Information Center will be closed weekends and bank\nholidays.\n\n**Order forms, along with full payment, must be received (not postmarked) no later than 2:00 p.m., Eastern\ntime, on June 16, 2026.**\n\n**The Merger**\n\n**Q:**\n\n**What will happen in the Merger?**\n\nA:\n\nThe Merger will be completed immediately after the completion of the Conversion. In the Merger, Northfield\nBancorp will merge with and into Columbia Financial, Inc., with Columbia Financial, Inc. continuing as the surviving corporation. Immediately following the Merger, Northfield Bank, the wholly owned subsidiary of Northfield Bancorp, will merge with\nand into Columbia Bank, the wholly owned subsidiary of Columbia Financial, Inc., with Columbia Bank continuing as the surviving institution (the “Bank Merger”). The completion of the Merger is subject to the completion of the Conversion\nand the satisfaction of other closing conditions.\n\nAfter the completion of the Merger, (i) Northfield Bancorp will\nno longer be a public company and will cease to exist, (ii) Northfield Bancorp common stock will be delisted from the Nasdaq Stock Market and will cease to be publicly\n\n4\n\n##### Table of Contents\n\ntraded, and (iii) Northfield Bancorp common stock will be deregistered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). After the completion of the\nMerger, Columbia Financial, Inc. stockholders (including stockholders who purchased shares of Columbia Financial, Inc. common stock in the Conversion offering) will continue to own their existing shares of Columbia Financial, Inc. common stock.\n\nSee the section of this Joint Proxy Statement/Prospectus captioned “*Description of the Merger*” for more information about\nthe Merger and the Merger Agreement. A copy of the Merger Agreement is also included as* Annex**** A* to this Joint Proxy Statement/Prospectus. You should read the Merger Agreement carefully and in its entirety.\n\n**Q:**\n\n**What will Northfield Bancorp stockholders receive in the Merger?**\n\nIf the Merger is completed, each share of Northfield Bancorp’s common stock, par value $0.01 per share, issued and outstanding\nimmediately prior to the effective time of the Merger, will be converted, at the election of the holder, into the right to receive either shares of Columbia Financial, Inc. common stock or cash, as follows: (i) if the final independent\nvaluation of Columbia Financial, Inc., immediately prior to the completion of the Conversion (the “Final Independent Valuation”), is less than $2.3 billion, 1.425 shares of Columbia Financial, Inc. common stock (the “Merger\nExchange Ratio”) or $14.25 in cash (the “Per Share Cash Consideration”); (ii) if the Final Independent Valuation is equal to or greater than $2.3 billion and less than $2.6 billion, the Merger Exchange Ratio will be\nincreased to 1.450 shares of Columbia Financial, Inc. common stock and the Per Share Cash Consideration will be increased to $14.50; or (iii) if the Final Independent Valuation is greater than $2.6 billion, the Merger Exchange Ratio will\nbe increased to 1.465 shares of Columbia Financial, Inc. and the Per Share Cash Consideration will be increased to $14.65. The “Final Independent Valuation” is also sometimes referred to herein as the “appraised full conversion\nvalue.” No more than 30% of the shares of Northfield Bancorp common stock issued and outstanding as of the effective time of the Merger (excluding shares of Northfield Bancorp common stock to be canceled as provided the Merger Agreement) will\nbe converted into the aggregate cash consideration. As of the date of this document, the current appraised full conversion value of Columbia Financial, Inc. is $2.291 billion at the midpoint of the offering range.\n\n**Q:**\n\n**What will Columbia Financial, Inc. stockholders receive in the Merger?**\n\nA:\n\nIn the Merger, Columbia Financial, Inc. stockholders will not receive any consideration, and their shares of\nColumbia Financial, Inc. common stock will remain outstanding and will constitute shares of Columbia Financial, Inc. common stock following the completion of the Merger. Following the completion of the Conversion and Merger, the common stock of\nColumbia Financial, Inc. is expected to be listed on the Nasdaq Global Select Market under the symbol “CLBK.”\n\n**Q:**\n\n**What equity stake will Columbia Financial, Inc. and Northfield Bancorp stockholders hold in the surviving\ncorporation immediately following the Merger?**\n\nBased on the number of shares of Northfield Bancorp common stock\noutstanding and reserved for issuance as of April 27, 2026, Columbia Financial, Inc. expects to issue approximately 41,800,140 shares of Columbia Financial, Inc. common stock in the Merger, assuming the Final Independent Valuation is\n$2,291 billion (the amount of the current independent valuation as of the date of this document) and 30% of the aggregate merger consideration consists of cash. Following the completion of the Merger, under such circumstances, former holders of\nNorthfield Bancorp common stock will own approximately 15.43% and existing holders of Columbia Financial, Inc. common stock (after giving effect to the Conversion) will own approximately 84.57% of the common stock of the surviving corporation at the\nmidpoint of the offering range.\n\n**Q:**\n\n**How will the Merger affect Northfield Bancorp equity awards?**\n\nA:\n\nImmediately prior to the effective time of the Merger, each outstanding unvested share of Northfield Bancorp\nrestricted stock that is subject to time-based vesting (the “Northfield Bancorp Restricted Stock”) will fully vest and be treated as an issued and outstanding share of Northfield Bancorp common stock for purposes of receiving the merger\nconsideration set forth in the Merger Agreement. Additionally, immediately prior to the effective time of the Merger, each outstanding unvested performance-based restricted stock unit with respect to Northfield Bancorp common stock (the\n“Northfield Bancorp PSRUs”) will fully vest, with any applicable performance-based vesting condition to be deemed achieved at the greater of the target level of performance or actual annualized performance measured as of the most recent\ncompleted fiscal quarter, and will be treated as an issued and outstanding share of Northfield Bancorp common stock for purposes of receiving the merger consideration set forth in the Merger Agreement. Columbia Financial, Inc. will not assume any\nNorthfield Bancorp Restricted Stock or Northfield Bancorp PSRUs in connection with the Merger.\n\nAt the effective time of\nthe Merger, each outstanding Northfield Bancorp stock option, whether vested or unvested, will fully vest and be converted automatically into an option to purchase shares of Columbia Financial, Inc. common stock\n\n5\n\n##### Table of Contents\n\nand will continue to be subject to the same terms and conditions as applied to the Northfield Bancorp stock option immediately prior to the effective time of the Merger. The number of shares of\nColumbia Financial, Inc. common stock subject to each assumed Northfield Bancorp stock option will be equal to the number of shares of Northfield Bancorp common stock subject to the stock option immediately prior to the effective time of the Merger,\nmultiplied by the Merger Exchange Ratio and rounded down to the nearest whole share. The per share exercise price of each assumed Northfield Bancorp stock option will also be adjusted by dividing the per share exercise price of the stock option by\nthe Merger Exchange Ratio, rounded up to the nearest cent.\n\n**Q:**\n\n**What are the material U.S. federal income tax consequences of the Merger to Northfield Bancorp stockholders?**\n\nA:\n\nThe Merger is intended to qualify as a “reorganization” within the meaning of Section 368(a)\nof the Internal Revenue Code of 1986, as amended (the “Code”) for U.S. federal income tax purposes, and each of Columbia Financial’s and Northfield Bancorp’s obligations to complete the Merger is conditioned on the receipt of\na legal opinion to the effect that the Merger will so qualify. Assuming the Merger qualifies as a reorganization, subject to the limitations and more detailed discussion set forth in the section entitled “*Description of the\nMerger—Material U.S. Federal Income Tax Consequences of the Merger*,” Northfield Bancorp stockholders generally will not recognize any gain or loss for U.S. federal income tax purposes on the exchange of their Northfield Bancorp\ncommon stock for Columbia Financial, Inc. common stock in the Merger, except for any gain or loss that may result from the receipt of the Per Share Cash Consideration or cash in lieu of a fractional share of Columbia Financial, Inc. common stock.\n\nThe tax consequences of the Merger to a particular Northfield Bancorp stockholder will depend in part on such\nstockholder’s individual circumstances. Accordingly, each Northfield Bancorp stockholder is urged to consult his or her own tax advisor for a full understanding of the tax consequences of the Merger to such stockholder, including the\napplicability and effect of U.S. federal, state, local and foreign income and other tax laws.\n\nFor further information concerning the U.S.\nfederal income tax consequences of the Merger, see the section of this Joint Proxy Statement/Prospectus captioned “*Description of the Merger—Material U.S. Federal Income Tax Consequences of the Merger.*”\n\n**Q:**\n\n**When do Columbia Financial, Inc. and Northfield Bancorp expect to complete the Merger?**\n\nA:\n\nThe parties expect to complete the Merger early in the third quarter of 2026; however, there is no assurance as\nto when or if the Merger will be completed. The completion of the Merger is subject to the completion of the Conversion and the satisfaction of other closing conditions. Prior to the consummation of the Merger, the stockholders of Columbia Financial\nmust approve the Columbia Conversion Proposal and the Columbia Merger Proposal, the stockholders of Northfield Bancorp must approve the Northfield Merger Proposal, and other conditions to the consummation of the Merger must be satisfied.\n\n**Q:**\n\n**Is the completion of the Merger contingent upon the completion of the Conversion?**\n\nYes, the completion of the Merger is subject to the completion of the Conversion and the satisfaction of other closing conditions.\n\n**Q:**\n\n**What are the conditions to complete the Merger?**\n\nA:\n\nThe obligations of Columbia Financial, Inc. and Northfield Bancorp to complete the Merger are subject to\n(i) the approval of the Merger Agreement by the stockholders of each of Columbia Financial and Northfield Bancorp, (ii) the authorization for listing on the Nasdaq Global Select Market of the shares of Columbia Financial, Inc. common stock\nthat will be issued as merger consideration; (iii) the receipt or provision of all non-governmental notices, consents or waivers by non-governmental third parties,\nexcept as would not reasonably be expected to have a material adverse effect on Columbia Financial, Columbia Financial, Inc. or Northfield Bancorp; (iv) the effectiveness of the Registration Statement on Form\nS-4 of which this Joint Proxy Statement/Prospectus is a part, and the absence of any stop order by the SEC suspending such effectiveness; (v) the receipt of all required regulatory approvals, in each case\nwithout the imposition of any materially burdensome regulatory condition (which we have conditionally received); (vi) no order, injunction or decree issued by any court or governmental entity or other legal restraint or prohibition preventing\nthe completion of the Merger or the Bank Merger; (vii) the deposit of cash and certificates representing sufficient shares of Columbia Financial, Inc. common stock sufficient to pay the merger consideration; (viii) approval of the\nConversion by the stockholders of Columbia Financial and by the members of Columbia Bank MHC, (ix) the completion of the Conversion; (x) the absence of any event that, individually or in the aggregate, has had or will reasonably be likely\nto have a material adverse effect on Northfield Bancorp or any of its subsidiaries; (xi) the accuracy of the representations and warranties of Columbia Financial, Columbia Financial, Inc., Columbia Bank MHC (together, the “Columbia\nParties”) and Northfield Bancorp contained in the Merger Agreement, both as of the date of the Merger Agreement and\n\n6\n\n##### Table of Contents\n\nas of the closing of the Merger, subject to the materiality standards provided for in the Merger Agreement; (xii) the performance in all material respects by each of the Columbia Parties and\nNorthfield Bancorp of their respective obligations, covenants and agreements required to be performed under the Merger Agreement; and (xiii) the receipt by each of the parties of an opinion of legal counsel that the Merger will qualify as a\n“reorganization” within the meaning of Section 368(a) of the Code.\n\n**Q:**\n\n**If the Merger is completed, when can Northfield Bancorp stockholders expect to receive the merger\nconsideration?**\n\nA:\n\nPromptly following the completion of the Merger, the exchange agent will send each former Northfield Bancorp\nstockholder of record instructions detailing how such stockholders can exchange their shares of Northfield Bancorp common stock for the merger consideration.\n\n**Q:**\n\n**What happens if the Merger is not completed?**\n\nA:\n\nIf the Merger is not completed, Northfield Bancorp stockholders will not receive any consideration for their\nshares of Northfield Bancorp common stock in connection with the Merger. Instead, Northfield Bancorp will remain an independent public company and Northfield Bancorp common stock will continue to be listed and traded on the Nasdaq Global Select\nMarket. In addition, if the Merger Agreement is terminated under certain circumstances, a termination fee will be payable by either Columbia Financial or Northfield Bancorp, as applicable. For further information, see the section of this Joint Proxy\nStatement/Prospectus captioned “*Description of the Merger—Termination Fee.*”\n\n**Q:**\n\n**Do stockholders of Northfield Bancorp have dissenters’ and appraisal rights in connection with the\nMerger?**\n\nA:\n\nUnder Section 262 of the Delaware General Corporation Law, holders of shares of Northfield Bancorp common\nstock may have the right to obtain an appraisal of the value of their shares of Northfield Bancorp common stock in connection with the Merger. To perfect appraisal rights, a Northfield Bancorp stockholder must not vote for the approval of the Merger\nAgreement and must strictly comply with all of the procedures required under Delaware law. Failure to strictly comply with Section 262 of the Delaware General Corporation Law may result in termination or waiver of appraisal rights.\n\n**Q:**\n\n**Do stockholders of Columbia Financial have dissenters’ and appraisal rights in connection with the\nMerger?**\n\nA:\n\nNo. Stockholders of Columbia Financial do not have dissenters’ rights in connection with the Merger.\n\n**The Columbia Financial Annual Meeting and the Northfield Bancorp Special Meeting**\n\n**Q:**\n\n**When and where will the Columbia Financial Annual Meeting and the Northfield Bancorp Special Meeting take\nplace?**\n\nA:\n\nThe Columbia Financial Annual Meeting will be held on June 25, 2026 at\nwww.virtualshareholdermeeting.com/CLBK2026 at 10:00 a.m., Eastern time.\n\nThe Northfield Bancorp Special Meeting will\nbe held on June 25, 2026 at www.virtualshareholdermeeting.com/NFBK2026SM at 9:00 a.m., Eastern time.\n\n**Q:**\n\n**What matters will be considered at the Columbia Financial Annual Meeting and the Northfield Bancorp Special\nMeeting?**\n\nA:\n\nAt the Columbia Financial Annual Meeting, Columbia Financial stockholders will be asked to consider and vote on\nthe following proposals:\n\n•\n\n*Columbia Financial Proposal No.**** 1:* The Columbia Conversion Proposal;\n\n•\n\n*Columbia Financial Proposal No.**** 2:* The Columbia Merger Proposal;\n\n•\n\n*Columbia Financial Proposal No.**** 3:* The Columbia Super-Majority Proposal;\n\n•\n\n*Columbia Financial Proposal No.**** 4:* The Columbia 10% Beneficial Owner Proposal;\n\n•\n\n*Columbia Financial Proposal No.**** 5:* The Columbia Director Election Proposal;\n\n•\n\n*Columbia Financial Proposal No.**** 6:* The Columbia Auditor Ratification Proposal;\n\n7\n\n##### Table of Contents\n\n•\n\n*Columbia Financial Proposal No.**** 7:* The Columbia Say-on-Pay Proposal;\n\n•\n\n*Columbia Financial Proposal No.**** 8:* The Columbia Say-on-Pay Frequency Proposal; and\n\n•\n\n*Columbia Financial Proposal No.**** 9:* The Columbia Adjournment Proposal.\n\nAt the Northfield Bancorp Special Meeting, Northfield Bancorp stockholders will be asked to consider and vote on the\nfollowing proposals:\n\n•\n\n*Northfield Bancorp Proposal No.**** 1:* The Northfield Merger Proposal;\n\n•\n\n*Northfield Bancorp Proposal No.**** 2:* The Northfield Merger-Related Compensation Proposal;\nand\n\n•\n\n*Northfield Bancorp Proposal No.**** 3:* The Northfield Adjournment Proposal.\n\nIn order to complete the Merger, among other things, Columbia Financial stockholders must approve the Columbia\nConversion Proposal and the Columbia Merger Proposal, and Northfield Bancorp stockholders must approve the Northfield Merger Proposal.\n\nNone of the approvals of the Columbia Super-Majority Proposal, the Columbia 10% Beneficial Owner Proposal, the Columbia Director Election\nProposal, the Columbia Auditor Ratification Proposal, the Columbia Say-on-Pay Proposal, the Columbia\nSay-on-Pay Frequency Proposal, the Columbia Adjournment Proposal, the Northfield Merger-Related Compensation Proposal or the Northfield Adjournment Proposal is a\ncondition to the obligation of the Columbia Parties or Northfield Bancorp to complete the Merger.\n\n**Q:**\n\n**How does the Columbia Financial board of directors recommend that I vote at the Columbia Financial Annual\nMeeting?**\n\nA:\n\nThe Columbia Financial board of directors unanimously recommends that Columbia Financial stockholders vote\n“FOR” the Columbia Conversion Proposal, “FOR” the Columbia Merger Proposal, “FOR” the Columbia Super-Majority Proposal, “FOR” the Columbia 10% Beneficial Owner Proposal, “FOR” the Columbia\nDirector Election Proposal, “FOR” the Columbia Auditor Ratification Proposal, “FOR” the Columbia Say-on-Pay Proposal, for “ONE YEAR”\nfor the Columbia Say-on-Pay Frequency Proposal and “FOR” the Columbia Adjournment Proposal.\n\n**Q:**\n\n**How does the Northfield Bancorp board of directors recommend that I vote at the Northfield Bancorp Special\nMeeting?**\n\nA:\n\nThe Northfield Bancorp board of directors unanimously recommends that Northfield Bancorp stockholders vote\n“FOR” the Northfield Merger Proposal, “FOR” the Northfield Merger-Related Compensation Proposal and “FOR” the Northfield Adjournment Proposal.\n\nCertain of Northfield Bancorp’s officers and directors have financial interests in the transactions contemplated by the Merger Agreement\nthat are different from, or in addition to, the interests of Northfield Bancorp stockholders. These interests are described in more detail in the section of this Joint Proxy Statement/Prospectus captioned “*Description of the\nMerger—Interests of Northfield Bancorp’s Directors and Executive Officers in the Merger.*”\n\n**Q:**\n\n**Who is entitled to vote at the Columbia Financial Annual Meeting?**\n\nA:\n\nThe holders of record of Columbia Financial common stock at the close of business on April 30, 2026, which\nis the date the Columbia Financial board of directors has fixed as the record date for the Columbia Financial Annual Meeting (the “Columbia Financial record date”) are entitled to vote at the Columbia Financial Annual Meeting.\n\nColumbia Financial stockholders are entitled to one vote for each share of Columbia Financial common stock held as of\nthe Columbia Financial record date. As of the close of business on the Columbia Financial record date, there were 104,142,951 outstanding shares of Columbia Financial common stock, including 76,016,524 shares held by Columbia Bank MHC.\n\nAttendance at the Columbia Financial Annual Meeting is not required to vote. See below and the section of this Joint Proxy Statement/Prospectus\ncaptioned “*Annual Meeting of Columbia Financial Stockholders—How to Vote*” for instructions on how to vote your shares of Columbia Financial common stock.\n\n**Q:**\n\n**Who is entitled to vote at the Northfield Bancorp Special Meeting?**\n\nA:\n\nThe holders of record of Northfield Bancorp common stock at the close of business on April 27, 2026, which\nis the date the Northfield Bancorp board of directors has fixed as the record date for the Northfield Bancorp Special Meeting (the “Northfield Bancorp record date”) are entitled to vote at the Northfield Bancorp Special Meeting.\n\n8\n\n##### Table of Contents\n\nNorthfield Bancorp stockholders are entitled to one vote for each share of Northfield\nBancorp common stock held as of the Northfield Bancorp record date. As of the close of business on the Northfield Bancorp record date, there were 41,763,852 outstanding shares of Northfield common stock.\n\nAttendance at the Northfield Bancorp Special Meeting is not required to vote. See below and the section of this Joint Proxy\nStatement/Prospectus captioned “*Special Meeting of Northfield Stockholders—How to Vote*” for instructions on how to vote your shares of Northfield Bancorp common stock.\n\n**Q:**\n\n**What constitutes a quorum for the Columbia Financial Annual Meeting?**\n\nA:\n\nA quorum, consisting of the holders of a majority of all the shares of Columbia Financial common stock entitled\nto vote at the Columbia Financial Annual Meeting, must be present in person or by proxy before any action may be taken at the Columbia Financial Annual Meeting. Once a share of Columbia Financial common stock is represented at the Columbia Financial\nAnnual Meeting, it will be counted for the purpose of determining a quorum not only at the Columbia Financial Annual Meeting but also at any adjournment or postponement of the Columbia Financial Annual Meeting. In the event that a quorum is not\npresent at the Columbia Financial Annual Meeting, it is expected that the Columbia Financial Annual Meeting will be adjourned or postponed. Abstentions and broker non-votes will not be counted for purposes of\ndetermining the number of votes cast on a proposal, but abstentions and broker non-votes will be treated as present for quorum purposes.\n\n**Q:**\n\n**What constitutes a quorum for the Northfield Bancorp Special Meeting?**\n\nA:\n\nA quorum, consisting of the holders of a majority of all the shares of Northfield Bancorp common stock entitled\nto vote at the Northfield Bancorp Special Meeting, must be present in person or by proxy before any action may be taken at the Northfield Bancorp Special Meeting. Once a share of Northfield Bancorp common stock is represented at the Northfield\nBancorp Special Meeting, it will be counted for the purpose of determining a quorum not only at the Northfield Bancorp Special Meeting but also at any adjournment or postponement of the Northfield Bancorp Special Meeting. In the event that a quorum\nis not present at the Northfield Bancorp Special Meeting, it is expected that the Northfield Bancorp Special Meeting will be adjourned or postponed. Abstentions and broker non-votes will not be counted for\npurposes of determining the number of votes cast on a proposal, but abstentions and broker non-votes will be treated as present for quorum purposes.\n\n**Q:**\n\n**What vote is required for the approval of each proposal at the Columbia Financial Annual Meeting?**\n\nA:\n\n*Columbia Financial Proposal No.**** 1: The Columbia Conversion Proposal.*Approval of the\nColumbia Conversion Proposal requires the affirmative vote of (i) two-thirds of the outstanding shares of Columbia Financial common stock entitled to vote on the proposal, including shares held by\nColumbia Bank MHC, and (ii) a majority of the outstanding shares of Columbia Financial common stock entitled to vote on the proposal, excluding shares held by Columbia Bank MHC. If you fail to submit a proxy or to vote in person at the Columbia\nFinancial Annual Meeting, mark “ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee (which we refer to as a broker non-vote) with respect to the Columbia Conversion\nProposal, it will have the same effect as a vote “AGAINST” such proposal.\n\n*Columbia Financial Proposal\nNo.**** 2: The Columbia Merger Proposal.*Approval of the Columbia Merger Proposal requires the affirmative vote of (i) two-thirds of the outstanding shares of Columbia Financial common\nstock entitled to vote on the proposal, including shares held by Columbia Bank MHC, and (ii) a majority of the outstanding shares of Columbia Financial common stock entitled to vote on the proposal, excluding shares held by Columbia Bank MHC.\nIf you fail to submit a proxy or to vote in person at the Columbia Financial Annual Meeting, mark “ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee (which we refer to as a broker non-vote) with respect to the Columbia Merger Proposal, it will have the same effect as a vote “AGAINST” such proposal.\n\n*Columbia Financial Proposal No.**** 3: The Columbia Super-Majority Proposal.*Approval of the informational Columbia\nSuper-Majority Proposal requires the affirmative vote of majority of the votes cast at the Columbia Financial Annual Meeting. If you fail to submit a proxy or vote in person at the Columbia Financial Annual Meeting, mark “ABSTAIN” on\nyour proxy or fail to instruct your bank, broker or other nominee with respect to the Columbia Super-Majority Proposal, it will have no effect on such proposal.\n\n*Columbia Financial Proposal No.**** 4: The Columbia 10% Beneficial Owner Proposal.*Approval of the informational Columbia\n10% Beneficial Owner Proposal requires the affirmative vote of majority of the votes cast at the Columbia Financial Annual Meeting. If you fail to submit a proxy or vote in person at the Columbia Financial Annual Meeting, mark “ABSTAIN”\non your proxy or fail to instruct your bank, broker or other nominee with respect to the Columbia 10% Beneficial Owner Proposal, it will have no effect on such proposal.\n\n*Columbia Financial Proposal No.**** 5: The Columbia Director Election Proposal.*Directors will be elected by a plurality\nof the votes cast at the Columbia Financial Annual Meeting. If you fail to submit a proxy or vote in person at the\n\n9\n\n##### Table of Contents\n\nColumbia Financial Annual Meeting or fail to instruct your bank, broker or other nominee with respect to the Columbia Financial Director Election Proposal, it will have no effect on such\nproposal.\n\n*Columbia Financial Proposal No.**** 6: The Columbia Auditor Ratification Proposal.*Approval of the\nColumbia Auditor Ratification Proposal requires the affirmative vote of majority of the votes cast at the Columbia Financial Annual Meeting. If you fail to submit a proxy or vote in person at the Columbia Financial Annual Meeting, mark\n“ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee with respect to the Columbia Auditor Ratification Proposal, it will have no effect on such proposal.\n\n*Columbia Financial Proposal No.**** 7: The Columbia\nSay-on-Pay Proposal.*Approval of the non-binding, advisory Columbia Say-on-Pay Proposal requires the affirmative vote of majority of the votes cast at the Columbia Financial Annual Meeting. If you fail to submit a proxy or vote in person at the Columbia Financial Annual\nMeeting, mark “ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee with respect to the Columbia Say-on-Pay Proposal, it will have\nno effect on such proposal.\n\n*Columbia Financial Proposal No.**** 8: The Columbia Say-on-Pay Frequency Proposal.*This non-binding, advisory proposal will be decided by the vote of a majority of the votes cast at the Columbia Financial Annual\nMeeting. Stockholders may vote for the frequency of “ONE YEAR,” “TWO YEARS,” or “THREE YEARS” or may “ABSTAIN.” Because this proposal has three choices, it is possible that no choice will receive a\nmajority of the votes cast. Under such circumstances, the Columbia Financial board of directors will consider the choice that receives the highest number of votes as the choice supported by stockholders. If you fail to submit a proxy or vote in\nperson at the Columbia Financial Annual Meeting, mark “ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee with respect to the Columbia\nSay-on-Pay Frequency Proposal, it will have no effect on such proposal.\n\n*Columbia Financial Proposal No.**** 9: The Columbia Adjournment Proposal.*Approval of the Columbia Adjournment Proposal\nrequires the affirmative vote of majority of the votes cast at the Columbia Financial Annual Meeting. If you fail to submit a proxy or vote in person at the Columbia Financial Annual Meeting, mark “ABSTAIN” on your proxy or fail to\ninstruct your bank, broker or other nominee with respect to the Columbia Adjournment Proposal, it will have no effect on such proposal.\n\nIt\nis anticipated that Columbia Bank MHC, the majority stockholder of Columbia Financial, will vote all of its shares in accordance with the recommendation of the Columbia Financial board of directors with respect to all proposals and director nominees\nto be presented at the Columbia Financial Annual Meeting. In addition, the Columbia Bank Foundation, in accordance with its governing documents, must vote all the shares of Columbia Financial in the same proportion as shares are voted by all other\nstockholders.\n\nThe certificate of incorporation of Columbia Financial provides that record holders of Columbia Financial’s common\nstock who beneficially own, either directly or indirectly, in excess of 10% of Columbia Financial’s outstanding shares are not entitled to any vote with respect to those shares held in excess of the 10% limit. This provision does not apply to\nshares held by Columbia Bank MHC.\n\n**Q:**\n\n**What vote is required for the approval of each proposal at the Northfield Bancorp Special Meeting?**\n\nA:\n\n*Northfield Bancorp Proposal No.**** 1: The Northfield Merger Proposal:*Approval of the\nNorthfield Merger Proposal requires the affirmative vote of a majority of the outstanding shares of Northfield Bancorp common stock entitled to vote on the proposal. If you fail to submit a proxy or to vote in person at the Northfield Bancorp\nSpecial Meeting, mark “ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee (which we refer to as a broker non-vote) with respect to the Northfield Merger Proposal, it will\nhave the same effect as a vote “AGAINST” such proposal.\n\n*Northfield Bancorp Proposal\nNo.**** 2: The Northfield Merger-Related Compensation Proposal.*Approval of the non-binding, advisory Northfield Merger-Related Compensation Proposal requires the affirmative vote of a\nmajority of the votes cast at the Northfield Bancorp Special Meeting. If you fail to submit a proxy or to vote in person at the Northfield Bancorp Special Meeting, mark “ABSTAIN” on your proxy or submit as a broker non-vote with respect to the Northfield Merger-Related Compensation Proposal, it will have no effect on such proposal.\n\n*Northfield Bancorp Proposal No.**** 3: The Northfield Adjournment Proposal.*Approval of the Northfield Adjournment\nProposal requires the affirmative vote of a majority of the votes cast at the Northfield Bancorp Special Meeting. If you fail to submit a proxy or to vote in person at the Northfield Bancorp Special Meeting, mark “ABSTAIN” on your proxy\nor fail to instruct your bank, broker or submit as a broker non-vote with respect to the Northfield Adjournment Proposal, it will have no effect on such proposal.\n\nThe certificate of incorporation of Northfield Bancorp provides that, subject to certain exceptions, shares of Northfield Bancorp common stock\nthat are beneficially owned by a person who beneficially owns in excess of 10% of the outstanding shares of Northfield Bancorp are not entitled to vote any of the shares held in excess of the 10% limit.\n\n10\n\n##### Table of Contents\n\n**Q:**\n\n**Why am I being asked to consider and vote on the Northfield Merger-Related Compensation Proposal?**\n\nA:\n\nUnder SEC rules, Northfield Bancorp is required to seek a non-binding,\nadvisory vote with respect to the compensation that may be paid or become payable to Northfield Bancorp’s named executive officers that is based on or otherwise relates to the Merger, or “golden parachute” compensation.\n\n**Q:**\n\n**What will happen if Northfield Bancorp stockholders do not approve the Northfield Merger-Related\nCompensation Proposal?**\n\nA:\n\nThe vote with respect to the Northfield Merger-Related Compensation Proposal is an advisory vote and will not\nbe binding on Northfield Bancorp or the Northfield Bancorp board of directors. Therefore, if the Northfield Merger Proposal is approved by Northfield Bancorp stockholders, the compensation described in the Northfield Merger-Related Compensation\nProposal could still be paid to the Northfield Bancorp named executive officers, if and to the extent required or allowed under applicable law, even if Northfield Bancorp stockholders do not approve the Northfield Merger-Related Compensation\nProposal.\n\n**Q:**\n\n**What if I hold shares in both Columbia Financial and Northfield Bancorp?**\n\nA:\n\nIf you hold shares of both Columbia Financial common stock and Northfield Bancorp common stock, you will\nreceive separate packages of proxy materials. A vote cast as a Columbia Financial stockholder will not count as a vote cast as a Northfield Bancorp stockholder, and a vote cast as a Northfield Bancorp stockholder will not count as a vote cast as a\nColumbia Financial stockholder. Therefore, please submit separate proxies for your shares of Columbia Financial common stock and your shares of Northfield Bancorp common stock.\n\n**Q:**\n\n**How can I vote my shares without attending the Columbia Financial Annual Meeting or the Northfield Bancorp\nSpecial Meeting?**\n\nA:\n\nWhether you hold your shares directly as the record holder of Columbia Financial common stock or Northfield\nBancorp common stock or beneficially in “street name,” you may direct your vote by proxy without attending the Columbia Financial Annual Meeting or the Northfield Bancorp Special Meeting, as applicable. If you are a record holder of\nColumbia Financial common stock or Northfield Bancorp common stock, you can vote your shares by proxy via the Internet, by mobile device or by mail by following the instructions provided in the enclosed proxy card. If your shares are held in\n“street name” and you wish to vote at the Columbia Financial Annual Meeting or the Northfield Bancorp Special Meeting, you will have to obtain a “legal proxy” from your broker, bank or other nominee entitling you to vote at\nthe Columbia Financial Annual Meeting or the Northfield Bancorp Special Meeting. If you hold shares beneficially in “street name” as a beneficial owner of Columbia Financial common stock or Northfield Bancorp common stock, you should\nfollow the voting instructions provided by your bank, broker, trustee or other nominee.\n\nColumbia Financial and\nNorthfield Bancorp recommend that you vote your shares in advance so that your vote will be counted if you later decide not to or become unable to attend the respective stockholder meeting.\n\nAdditional information on voting procedures can be found under the sections of this Joint Proxy Statement/Prospectus captioned “*Annual\nMeeting of Columbia Financial Stockholders—How to Vote*” and “*Special Meeting of Northfield Bancorp Stockholders—How to Vote.*”\n\n**Q:**\n\n**What do I need to do now?**\n\nA:\n\nRead and consider the information contained in this Joint Proxy Statement/Prospectus, including the Annexes,\ncarefully and then please submit as soon as possible either your Columbia Financial proxy, in the case of Columbia Financial stockholders, or your Northfield Bancorp proxy, in the case of Northfield Bancorp stockholders.\n\n**Q:**\n\n**If my shares of Columbia Financial common stock or Northfield Bancorp common stock are held in street name\nby my broker, will my broker automatically vote my shares for me?**\n\nA:\n\nNo. Your bank, broker or other nominee will not be able to vote shares held by it in street name on your behalf\nwithout instructions from you. You should instruct your bank, broker or other nominee to vote your shares by following the directions your bank, broker or other nominee provides to you. Please check the voting instructions form used by your bank,\nbroker or other nominee.\n\n**Q:**\n\n**What is a broker non-vote?**\n\nA:\n\nA “broker non-vote” occurs when a broker, bank or other\nnominee holding shares on your behalf does not receive voting instructions from you. If that happens, the broker, bank or other nominee may vote those shares only on matters deemed\n\n11\n\n##### Table of Contents\n\n“routine” under the rules of the NYSE, which govern the use of broker non-votes at the Columbia Financial Annual Meeting and the Northfield\nBancorp Special Meeting despite the fact that Columbia Financial and Northfield Bancorp are both listed on the Nasdaq Global Select Market. On non-routine matters, the broker, bank or other nominee cannot vote\nthose shares unless they receive voting instructions from the beneficial owner. A “broker non-vote” occurs when a broker has not received voting instructions and either declines to exercise its\ndiscretionary authority to vote on routine matters or is barred from doing so because the matter is non-routine. The Northfield Merger Proposal, the Northfield Merger-Related Compensation Proposal, and the\nNorthfield Adjournment Proposal are considered to be “non-routine” under NYSE rules such that your broker, bank or other agent may not vote your shares on those proposals in the absence of your\nvoting instructions. The Columbia Conversion Proposal, the Columbia Merger Proposal, the Columbia Super-Majority Proposal, the Columbia 10% Beneficial Owner Proposal, the Columbia Director Election Proposal, the Columbia Say-on-Pay Proposal, the Columbia Say-on-Pay Frequency Proposal and the Columbia Adjournment\nProposal are considered to be “non-routine” under NYSE rules such that your broker, bank or other agent may not vote your shares on those proposals in the absence of your voting instructions. The\nColumbia Auditor Ratification Proposal is considered to be a “routine” matter, such that your broker, bank or other agent may vote your shares in its discretion in the absence of your voting instructions.\n\n**Q:**\n\n**What if I abstain from voting or fail to instruct my bank, broker or other nominee?**\n\nA:\n\nFor the purposes of the Columbia Financial Annual Meeting, an abstention occurs when a Columbia Financial\nstockholder attends the Columbia Financial Annual Meeting and does not vote or returns a proxy with an “ABSTAIN” instruction. In the event that a quorum is present, abstentions and broker non-votes\nof shares of Columbia Financial common stock will have the same effect as a vote “AGAINST” the Columbia Conversion Proposal and the Columbia Merger Proposal. Abstentions and broker non-votes of\nshares of Columbia Financial common stock will not have any effect on the approval of the Columbia Super-Majority Proposal, the Columbia 10% Beneficial Owner Proposal, the Columbia Director Election Proposal, the Columbia Auditor Ratification\nProposal, the Columbia Say-on-Pay Proposal, the Columbia Say-on-Pay Frequency Proposal or\nthe Columbia Adjournment Proposal.\n\nFor purposes of the Northfield Bancorp Special Meeting, an abstention occurs when a\nNorthfield Bancorp stockholder attends the Northfield Bancorp Special Meeting and does not vote or returns a proxy with an “ABSTAIN” instruction. In the event that a quorum is present, abstentions and broker non-votes of shares of Northfield Bancorp common stock will have the same effect as a vote “AGAINST” the Northfield Merger Proposal. Abstentions and broker\nnon-votes of shares of Northfield Bancorp common stock will not have any effect on the approval of the Northfield Merger-Related Compensation Proposal or the Northfield Adjournment Proposal at the Northfield\nBancorp Special Meeting.\n\n**Q:**\n\n**Why is my vote important?**\n\nA:\n\nThe Conversion and Merger cannot be completed unless Columbia Financial stockholders approve the Columbia\nConversion Proposal and the Columbia Merger Proposal, and Northfield Bancorp stockholders approve the Northfield Merger Proposal, which are the only applicable Columbia Financial and Northfield Bancorp stockholder proposals necessary to complete the\nConversion and the Merger.\n\nInformation about the Columbia Financial Annual Meeting, the Northfield Bancorp Special\nMeeting, the Conversion and the Merger, as well as other matters to be considered by stockholders of each of Columbia Financial and Northfield Bancorp, is contained in this document.\n\n**Q:**\n\n**What if I am a record holder and I do not indicate a decision with respect to the matters required to be\nvoted on?**\n\nA:\n\nIf you are a record holder of Columbia Financial common stock or Northfield Bancorp common stock and you\nreturned a signed proxy card without indicating how to vote on any particular proposal, the shares of Columbia Financial common stock represented by your proxy will be voted as recommended by the Columbia Financial board of directors with respect to\nsuch proposals, or the shares of Northfield Bancorp common stock represented by your proxy will be voted as recommended by the Northfield Bancorp board of directors with respect to such proposals, as the case may be.\n\n**Q:**\n\n**Can I change my vote?**\n\nA:\n\nYes. You may revoke your proxy at any time before it is exercised.\n\nColumbia Financial stockholders that are stockholders of record must give written notice of revocation to the Corporate Secretary of Columbia\nFinancial, submit another properly signed proxy with a more recent date, vote again via the Internet or by telephone, or vote at the Columbia Financial Annual Meeting. Please note that simply participating in the Columbia Financial Annual Meeting in\nperson without voting will not revoke your proxy.\n\n12\n\n##### Table of Contents\n\nYou may revoke a proxy for shares held by a bank, broker, or other nominee by submitting new\nvoting instructions to the bank, broker, or other nominee or, if you have obtained a legal proxy from the bank, broker, or other nominee giving you the right to vote the shares at the Columbia Financial Annual Meeting, by following the voting\ninstructions provided in the legal proxy.\n\nNorthfield Bancorp stockholders that are stockholders of record must file a written revocation\nwith the Corporate Secretary of Northfield Bancorp, submit a new proxy by telephone or the Internet, or submit a new proxy card after the time and date of the previously submitted proxy card, or virtually attend the Northfield Bancorp Special\nMeeting and vote at the Northfield Bancorp Special Meeting. Simply virtually attending the Northfield Bancorp Special Meeting without voting will not revoke a Northfield Bancorp proxy.\n\nIf you have instructed a bank, broker or other nominee to vote your shares of Northfield Bancorp common stock, you must follow directions\nreceived from the bank, broker or other nominee to change his or her vote. Revocation of a proxy or a later-dated proxy received by Northfield Bancorp after the vote will not affect the vote. Virtual attendance at the Northfield Bancorp Special\nMeeting will not, in and of itself, constitute revocation of a proxy.\n\n**Q:**\n\n**Will Columbia Financial be required to submit the Columbia Merger Proposal to its stockholders even if the\nColumbia Financial board of directors has withdrawn, modified or qualified its recommendation?**\n\nA:\n\nYes. Unless the Merger Agreement is terminated before the Columbia Financial Annual Meeting, Columbia Financial\nis required to submit the Columbia Merger Proposal to Columbia Financial stockholders even if the Columbia Financial board of directors has withdrawn, modified or qualified its recommendation.\n\n**Q:**\n\n**Will Northfield Bancorp be required to submit the Northfield Merger Proposal to its stockholders even if the\nNorthfield Bancorp board of directors has withdrawn, modified or qualified its recommendation?**\n\nA:\n\nYes. Unless the Merger Agreement is terminated before the Northfield Bancorp Special Meeting, Northfield\nBancorp is required to submit the Northfield Merger Proposal to Northfield Bancorp stockholders even if the Northfield Bancorp board of directors has withdrawn, modified or qualified its recommendation.\n\n**Q:**\n\n**Are there any risks that should be considered in deciding whether to vote for the matters required to be\nvoted on by the respective stockholders of Columbia Financial and Northfield Bancorp?**\n\nA:\n\nYes. The section of this Joint Proxy Statement/Prospectus captioned “*Risk Factors*” sets\nforth a number of risk factors that Columbia Financial stockholders and Northfield Bancorp stockholders should consider carefully.\n\n**Q:**\n\n**What happens if I sell my shares after the applicable record date but before the Columbia Financial Annual\nMeeting or Northfield Bancorp Special Meeting, as applicable?**\n\nA:\n\nEach of the Columbia Financial record date and the Northfield Bancorp record date is earlier than the date of\nthe Columbia Financial Annual Meeting and the Northfield Bancorp Special Meeting, as applicable, and earlier than the date that the Conversion and the Merger are expected to be completed. If you sell or otherwise transfer your shares of Columbia\nFinancial common stock or Northfield Bancorp common stock, as applicable, after the applicable record date but before the date of the applicable stockholder meeting, you will retain your right to vote at such stockholder meeting (provided that such\nshares remain outstanding on the date of such stockholder meeting), but, with respect to Northfield Bancorp common stock, you will not have the right to receive the merger consideration to be received by Northfield Bancorp stockholders in connection\nwith the Merger. In order to receive the merger consideration, you must hold your shares of Northfield Bancorp common stock through the completion of the Merger.\n\n**Q:**\n\n**What should I do if I receive more than one set of voting materials for the same stockholder meeting?**\n\nA:\n\nIf you are a beneficial owner and hold shares of Columbia Financial common stock or Northfield Bancorp common\nstock in “street name” and also are a record holder and hold shares directly in your name or otherwise or if you hold shares of Columbia Financial common stock or Northfield Bancorp common stock in more than one brokerage account, you\nmay receive more than one set of voting materials relating to the same special meeting.\n\n*Record Holders*. For\nshares held directly, please complete, sign, date and return each proxy card (or cast your vote by telephone or the Internet as provided on each proxy card) or otherwise follow the voting instructions provided in this Joint Proxy\nStatement/Prospectus in order to ensure that all of your shares of Columbia Financial common stock or Northfield Bancorp common stock are voted.\n\n*Beneficial Owners*. For shares held in “street name” through a bank, broker, trustee or other nominee, you should follow the\nprocedures provided by your bank, broker, trustee or other nominee in order to vote your shares.\n\n13\n\n##### Table of Contents\n\n**Additional Questions**\n\n**Q:**\n\n**Where can I find more information about Columbia Financial and Northfield Bancorp?**\n\nA:\n\nYou can find more information about Columbia Financial and Northfield Bancorp from the various sources\ndescribed under the section of this Joint Proxy Statement/Prospectus captioned “*Where You Can Find More Information.*”\n\n**Q:**\n\n**Whom should I call if I have questions?**\n\nA:\n\nIf you are a Columbia Financial stockholder and have any questions concerning the Conversion, the Merger or\nthis Joint Proxy Statement/Prospectus, would like additional copies of this Joint Proxy Statement/Prospectus or need help voting your shares of Columbia Financial common stock, please contact Columbia Financial’s proxy solicitor, The Laurel\nHill Advisory Group, LLC (“Laurel Hill”), by calling toll-free at (888) 742-1305 and (516) 933-3100 for banks and brokers.\n\nIf you are a Northfield Bancorp stockholder and have any questions concerning the Merger or this Joint Proxy Statement/Prospectus, would like\nadditional copies of this Joint Proxy Statement/Prospectus or need help voting your shares of Northfield Bancorp common stock, please contact Northfield Bancorp’s proxy solicitor, Lioness Consulting LLC, by calling toll-free at (833) 820-9861,\nor by e-mail at NFBK@lionessconsultingllc.com.\n\nIf you would like to receive a prospectus and stock order form for the Conversion offering,\nplease call Columbia Financial, Inc.’s Stock Information Center at (844) 265-9680 from 10:00 a.m. to 4:00 p.m., Eastern time, Monday through Friday. The Stock Information Center will be\nclosed weekends and bank holidays.\n\n14\n\n##### Table of Contents\n\n**SUMMARY**\n\n*This summary highlights selected information in this document and may not contain all of the information important to you. To understand\nthe Conversion and the Merger more fully, you should read this entire document carefully, including the annexes and the documents attached to or incorporated by reference into this document*. *In this summary, the terms “we,”\n“us” and “our” refer to Columbia Financial and its consolidated subsidiaries or its successor Columbia Financial, Inc., Columbia****Bank MHC and Columbia Bank unless the context requires otherwise.*\n\n**The Companies**\n\n**Information\nAbout the Companies**\n\n**Columbia Financial, Inc. (a Delaware corporation)**\n\n**Columbia Financial, Inc. (a Maryland corporation)**\n\n**Columbia Bank MHC**\n\n**Columbia Bank**\n\n19-01 Route 208 North\n\nFair Lawn, New Jersey 07410\n\nColumbia Financial, a Delaware corporation, is the mid-tier stock holding company of Columbia Bank, a\nfederally chartered stock savings bank that has elected to operate as a “covered savings association” under the rules and regulations of the Office of the Comptroller of the Currency (the “OCC”). Columbia Financial was\norganized in March 1997 in connection with the mutual holding company reorganization of Columbia Bank. Columbia Bank MHC, the parent mutual holding company of Columbia Bank, was also organized in 1997 under the laws of the United States. In\nconnection with the reorganization, Columbia Financial became the wholly owned subsidiary of Columbia Bank MHC. Columbia Financial currently owns all of the outstanding shares of common stock of Columbia Bank.\n\nColumbia Bank is a federally chartered savings bank founded in 1927 that operates 70 full-service banking offices and offers traditional\nfinancial services to consumers and businesses in its market area. Columbia Bank serves the financial needs of its depositors and the local community as a community-minded, customer service-focused institution. Columbia Bank offers traditional\nfinancial services to businesses and consumers in its market areas. Columbia Bank attracts deposits from the general public and uses those funds to originate a variety of loans, including multi-family and commercial real estate loans, commercial\nbusiness loans, one-to-four family real estate loans, construction loans, home equity loans and advances, and other consumer loans. Columbia Bank offers title insurance\nthrough its wholly-owned subsidiary, First Jersey Title Services, Inc., In addition, Columbia Insurance Services, Inc. (formerly known as “RSI Insurance Agency, Inc.”), a wholly-owned subsidiary of Columbia Bank, is a full-service\ninsurance agency that offers a broad range of insurance products and investment solutions, including personal and business lines of insurance, to customers that are primarily New Jersey residents. Wealth management services are also offered through\na third-party relationship.\n\nColumbia Financial, Inc. is a newly formed Maryland corporation. Following the completion of the Conversion,\nColumbia Financial, Inc. will become the publicly-traded savings and loan holding company for Columbia Bank. Shares of Columbia Financial, Inc.’s common stock are expected to trade on the Nasdaq Global Select Market under the symbol\n“CLBK” upon the completion of the Conversion.\n\nColumbia Bank’s website address is www.columbiabankonline.com.\nInformation on Columbia Bank’s website should not be considered a part of this document.\n\n**Northfield Bancorp, Inc.**\n\n**Northfield Bank**\n\n581 Main Street, Suite 810\n\nWoodbridge, New Jersey 07095\n\nNorthfield Bancorp, a Delaware corporation was organized in 2010 and is the holding company for Northfield Bank. Northfield Bank was organized\nin 1887 and is a federally chartered savings bank. Northfield Bank conducts business from its operations center located in Woodbridge, New Jersey, its home office located at a branch in Staten Island, New York, and its 37 additional branch offices\nlocated in Staten Island, Brooklyn, and the New Jersey counties of Hunterdon, Mercer, Middlesex, and Union. Northfield Bank also offers select loan and deposit products through the internet.\n\n15\n\n##### Table of Contents\n\nNorthfield Bank’s principal business consists of originating multifamily and\ncommercial real estate loans, construction and land loans, commercial and industrial loans, home equity loans and lines of credit, and one- to four-family residential real estate loans. From time to time\nNorthfield Bank will also purchase loan participations and pools of loans. Northfield Bank also purchases investment securities, including mortgage-backed securities and corporate bonds, and, to a lesser extent, deposit funds in other financial\ninstitutions, including the Federal Reserve Bank of New York and the Federal Home Loan Bank of New York. Northfield Bank offers a variety of deposit accounts, including transaction accounts, savings accounts, including passbook, statement, money\nmarket savings and certificate of deposit accounts, all of which are Northfield Bank’s primary source of funds for its lending and investing activities. Northfield Bank also borrows funds, principally through Federal Home Loan Bank of New York\nadvances, repurchase agreements and wholesale deposits with brokers. Northfield Bank owns 100% of NSB Services Corp., which, in turn, owns 100% of the voting common stock of a real estate investment trust, NSB Realty Trust, which holds primarily\nmortgage loans.\n\nNorthfield Bank’s website address is www.enorthfield.com. Information on Northfield Bank’s website should not\nbe considered a part of this document.\n\n**The Columbia Financial Annual Meeting and the Northfield Bancorp Special Meeting**\n\n**The Columbia Financial Annual Meeting (page 57)**\n\nThe Columbia Financial Annual Meeting will be held on June 25, 2026 at www.virtualshareholdermeeting.com/CLBK2026 at 10:00 a.m., Eastern\ntime.\n\nAt the Columbia Financial Annual Meeting, Columbia Financial stockholders will be asked to vote on the Columbia Conversion\nProposal, the Columbia Merger Proposal, the Columbia Super-Majority Proposal, the Columbia 10% Beneficial Owner Proposal, the Columbia Director Election Proposal, the Columbia Auditor Ratification Proposal, the Columbia Say-on-Pay Proposal and the Columbia Say-on-Pay Frequency Proposal, and may be asked to vote on\nthe Columbia Adjournment Proposal if there are not sufficient votes at the Columbia Financial Annual Meeting to approve the Columbia Conversion Proposal or the Columbia Merger Proposal.\n\nOnly Columbia Financial stockholders of record as of the close of business on April 30, 2026 are entitled to notice of, and to vote at,\nthe Columbia Financial Annual Meeting and any adjournments or postponements of the Columbia Financial Annual Meeting. As of April 30, 2026, the record date for the Columbia Financial Annual Meeting, there were 104,142,951 shares of Columbia\nFinancial common stock outstanding, including 76,016,524 shares owned by Columbia Bank MHC. \n\nThe affirmative vote of a majority of\nall the votes entitled to be cast at the Columbia Financial Annual Meeting by stockholders other than Columbia Bank MHC is required to approve the Columbia Conversion Proposal and the Columbia Merger Proposal. The Columbia Super-Majority Proposal,\nthe Columbia 10% Beneficial Owner Proposal, the Columbia Auditor Ratification Proposal, the Columbia Say-on-Pay Proposal and the Columbia Adjournment Proposal must each\nbe approved by the affirmative vote of the majority of the votes cast at the Columbia Financial Annual Meeting. Directors will be elected by a plurality of votes cast at the Columbia Financial Annual Meeting. For the Columbia Say-on-Pay Frequency Proposal, the choice of frequency that receives the highest votes will be considered the advisory vote of stockholders.\n\n**The Northfield Bancorp Special Meeting (page 73)**\n\nThe Northfield Bancorp Special Meeting will be held on June 25, 2026 at www.virtualshareholdermeeting.com/NFBK2026SM at 9:00 a.m., Eastern\ntime.\n\nAt the Northfield Bancorp Special Meeting, Northfield Bancorp stockholders will be asked to vote on the Northfield Merger Proposal,\nthe Northfield Merger-Related Compensation Proposal, and may be asked to vote on the Northfield Adjournment Proposal if there are not sufficient votes at the Northfield Bancorp Special Meeting to approve the Northfield Merger Proposal.\n\nOnly Northfield Bancorp stockholders of record as of the close of business on April 27, 2026 are entitled to notice of, and to vote at,\nthe Northfield Bancorp Special Meeting and any adjournments or postponements of the Northfield Bancorp Special Meeting. As of April 27, 2026, the record date for the Northfield Bancorp Special Meeting, there were 41,763,852 shares of\nNorthfield Bancorp common stock outstanding. \n\n16\n\n##### Table of Contents\n\nApproval of the Northfield Merger Proposal requires the affirmative vote of a majority of\nthe outstanding shares of Northfield Bancorp common stock entitled to vote on the proposal. Approval of the Northfield Merger-Related Compensation Proposal and the Northfield Adjournment Proposal requires the affirmative vote of a majority of the\nvotes cast at the Northfield Bancorp Special Meeting.\n\n**The Conversion**\n\n**Description of the Conversion (page 81)**\n\nColumbia Bank has been organized in the mutual holding company structure since 1997. The following diagram shows our current organizational\nstructure, reflecting ownership percentages as of December 31, 2025:\n\nThe “second-step” conversion process that Columbia Financial is now undertaking involves a\nseries of transactions by which Columbia Financial will convert its organization from the partially public mutual holding company form to the fully public stock holding company structure. In the stock holding company structure, all of Columbia\nBank’s common stock will be owned by Columbia Financial, Inc. and all of Columbia Financial, Inc.’s common stock will be owned by the public. Upon completion of the Conversion and offering, Columbia Financial and Columbia Bank MHC will\ncease to exist.\n\nAs part of the Conversion, Columbia Financial, Inc. is offering for sale shares of common stock representing the 73.1%\nownership interest of Columbia Financial that is currently held by Columbia Bank MHC. At the conclusion of the Conversion and offering, existing public stockholders of Columbia Financial will receive shares of common stock of Columbia Financial,\nInc. in exchange for their existing shares of common stock of Columbia Financial, based upon an exchange ratio of 1.8729 to 2.5340 at the minimum and maximum of the offering range, respectively. The actual exchange ratio will be determined at the\nconclusion of the Conversion and the offering based on the total number of shares sold in the offering and is intended to result in Columbia Financial’s existing public stockholders owning approximately the same percentage interest, 26.9%\nof Columbia Financial, Inc. common stock as they currently own of Columbia Financial common stock, without giving effect to cash paid in lieu of issuing fractional shares or shares that existing stockholders may purchase in the offering or shares\nissued in the Northfield Bancorp acquisition. For more information, see “— *The Exchange of Existing Shares of Columbia Financial Common Stock.”*\n\n17\n\n##### Table of Contents\n\nAfter the Conversion and offering, and completion of the Merger, our ownership structure\nwill be as follows:\n\nThe normal business operations of Columbia Bank will continue without interruption during the Conversion\nand offering. The executive officers and the directors who will serve on the boards of directors of Columbia Financial and Columbia Bank following Columbia Financial’s 2026 annual meeting of stockholders will serve as executive officers and\ndirectors of Columbia Financial, Inc. and Columbia Bank following completion of the Conversion.\n\nImmediately following the completion of\nthe Conversion, Northfield Bancorp will merge with and into Columbia Financial, Inc. and Northfield Bank will merge with and into Columbia Bank. Prior to the effective time of the Merger Columbia Financial, Inc. will increase the size of its board\nof directors by four members (to 13 directors). As of the effective time of the Merger, the board of directors of Columbia Financial, Inc. will be comprised of the nine legacy Columbia Financial directors and four members of the Northfield Bancorp\nboard of directors selected by Columbia Financial, one of whom shall be Steven M. Klein. In addition, at the effective time of the Merger, Steven M. Klein will serve as Senior Executive Vice President and Chief Operating Officer of Columbia\nFinancial, Inc. and Columbia Bank.\n\n**Reasons for the Conversion and Offering (page 80)**\n\nColumbia Financial’s primary reasons for the Conversion and offering are as follows:\n\n•\n\n**Facilitate our acquisition of Northfield Bancorp.**The stock holding company structure enables us to\nacquire Northfield Bancorp through a combination of common stock and cash consideration, which is not possible in our current mutual holding company form of organization.\n\n•\n\n**To enhance stockholder returns through higher earnings and more flexible capital management\nstrategies.**\n\n•\n\n**To pay dividends on our common stock.**The stock holding company structure will eliminate the\ncurrent limitations imposed by the mutual holding company structure on dividend payments and make it less costly for us to pay dividends.\n\n•\n\n**Strengthen our capital position with the additional capital we will raise in the offering to support our\nplanned growth.** A strong capital position is essential to achieving our long-term objectives of growing Columbia Bank and building stockholder value. While Columbia Bank exceeds all regulatory capital requirements, the proceeds from the\noffering will greatly strengthen our capital position and enable us to support our planned growth in accordance with our strategic plan.\n\n•\n\n**Transition us to a more familiar and flexible organizational structure.** The stock holding company\nstructure is a more familiar form of organization, which we believe will make our common stock more appealing to investors and enhance the liquidity of our common stock. A more liquid and active market will make it easier for our stockholders to buy\nand sell our common stock and will give us greater flexibility in implementing capital management strategies. The stock holding company structure will also give us greater flexibility to access the capital markets through possible future equity and\ndebt offerings, although we have no current plans or arrangements for any such offerings.\n\n18\n\n##### Table of Contents\n\n•\n\n**Facilitate future mergers and acquisitions.** Although we do not currently have any understandings or\nagreements regarding any specific acquisition transactions, other than our pending merger with Northfield Bancorp, the stock holding company structure will give us greater flexibility to structure, and make us a more attractive and competitive\nbidder for, mergers and acquisitions of other financial institutions and/or financial services companies as opportunities arise.\n\n**Conditions to Completing the Conversion and Offering (page 81)**\n\nColumbia Financial cannot complete the Conversion and offering unless:\n\n•\n\nwe sell at least the minimum number of shares offered (after giving effect to the adjusted minimum of the\noffering range, if applicable);\n\n•\n\nwe receive the approval of the Federal Reserve Board to complete the Conversion and offering and to acquire\nColumbia Bank in connection with the Conversion and offering;\n\n•\n\nthe Plan of Conversion is approved by at least *a majority of votes eligible to be cast* by members of\nColumbia Bank MHC;\n\n•\n\nthe Plan of Conversion is approved by at least *two-thirds of the\noutstanding shares* of Columbia Financial, including shares held by Columbia Bank MHC; and\n\n•\n\nthe Plan of Conversion is approved by at least *a majority of the votes eligible to be cast* by stockholders\nof Columbia Financial, excluding shares held by Columbia Bank MHC.\n\nColumbia Bank MHC, which owns 73.1% of the\noutstanding shares of Columbia Financial, intends to vote these shares in favor of the Plan of Conversion. This would guarantee that the Plan of Conversion is approved by at least two-thirds of the outstanding\nshares of Columbia Financial, including shares held by Columbia Bank MHC. In addition, as of April 30, 2026, directors and executive officers of Columbia Financial and their associates beneficially owned 3,904,821 shares of Columbia\nFinancial, or 3.75% of the outstanding shares of Columbia Financial, and they intend to vote those shares in favor of the plan of conversion.\n\nIn addition, each of the directors of Columbia Financial has entered into a support agreement pursuant to which, among other things, each such\ndirector has agreed, subject to the terms of the support agreement, to vote the shares of Columbia Financial common stock over which he or she has the sole power to vote or direct the voting of in favor of the approval of the Plan of Conversion. As\nof April 30, 2026, the members of the board of directors of Columbia Financial owned and held the sole dispositive and voting power over 1,195,072 shares of Columbia Financial common stock.\n\nIn the event that the Merger with Northfield Bancorp is terminated, Columbia Financial may determine to terminate the Conversion or delay the\nConversion. If it determines to delay the Conversion, the timing and manner of the conversion would be subject to significant modification and subscribers would have the right to modify or rescind their purchase orders.\n\nAs of the date of this joint proxy statement/prospectus, (i) the Federal Reserve Board has conditionally approved the Conversion and offering\nand (ii) the Federal Reserve Board and the OCC have conditionally approved the Merger and the Bank Merger, respectively.\n\n**The Exchange of Existing\nShares of Columbia Financial Common Stock (page 82)**\n\nIf you are a stockholder of Columbia Financial on the date the Conversion and\noffering are completed, your existing shares will be canceled and exchanged for shares of Columbia Financial, Inc. The number of shares you will receive will be based on an exchange ratio determined as of the completion of the Conversion and\noffering. The following table shows how the exchange ratio will adjust, based on the appraised value of Columbia Financial as of February 2, 2026, and assuming public stockholders of Columbia Financial own 26.9% of Columbia Financial common\nstock immediately prior to the completion of the Conversion. The table also shows how many shares of Columbia Financial, Inc., a hypothetical owner of Columbia Financial common stock, would receive in the exchange for 100 shares of common stock\nowned at the completion of the Conversion, depending on the number of shares issued\n\n19\n\n##### Table of Contents\n\nin the offering. Information is presented at the adjusted minimum, which reflects the discretionary issuance of shares to Northfield Bancorp stockholders, and at the minimum, midpoint and maximum\nof the offering range.\n\n**Shares to be Sold**\n**in the Offering**\n\n**Shares to beExchanged for ExistingShares of ColumbiaFinancial**\n\n**Total Sharesof CommonStock Issuedin theExchange andSold in theOffering(1)**\n\n**MinorityStockholder**\n**ExchangeRatio**\n\n**Equivalentper ShareValue(2)**\n\n**Sharesto beReceivedfor 100ExistingShares(3)**\n\n**Amount**\n\n**Percent**\n\n**Amount**\n\n**Percent**\n\nAdjusted Minimum\n\n142,375,000\n(4)\n\n73.1\n%\n\n52,382,845\n\n26.9\n%\n\n194,757,845\n\n1.8729\n\n$\n18.73\n\n187\n\nMinimum\n\n142,375,000\n\n73.1\n%\n\n52,382,845\n\n26.9\n%\n\n194,757,845\n\n1.8729\n\n$\n18.73\n\n187\n\nMidpoint\n\n167,500,000\n\n73.1\n%\n\n61,626,877\n\n26.9\n%\n\n229,126,877\n\n2.2035\n\n$\n22.04\n\n220\n\nMaximum\n\n192,625,000\n\n73.1\n%\n\n70,870,908\n\n26.9\n%\n\n263,495,908\n\n2.5340\n\n$\n25.34\n\n253\n\n(1)\n\nRepresents the appraised full conversion appraised value of Columbia Financial of $1.948 billion at the\nadjusted minimum and the minimum, $2.291 billion at the midpoint and $2.635 billion at the maximum based on an offering price of $10.00 per share.\n\n(2)\n\nRepresents the value of shares of Columbia Financial, Inc. common stock received in the Conversion by a holder\nof one share of Columbia Financial common stock at the exchange ratio, assuming a market price of  $10.00 per share.\n\n(3)\n\nCash will be paid instead of issuing any fractional shares.\n\n(4)\n\nIncludes 41,800,140 shares that may be issued as merger consideration to meet the minimum offering requirement,\nassuming 70% of the merger consideration is in stock, and which will be considered shares sold in the community offering for purposes of the offering range.\n\nNo fractional shares of Columbia Financial, Inc. common stock will be issued in the Conversion and offering. For each fractional share that\nwould otherwise be issued, Columbia Financial, Inc. will pay cash in an amount equal to the product obtained by multiplying the fractional share interest to which the holder would otherwise be entitled by the $10.00 per share offering price.\n\n**Effect of the Conversion on Stockholders of Columbia Financial (page 83)**\n\nThe following table shows the total number of shares of Columbia Financial, Inc. common stock that will be outstanding after the completion of\nthe offering, the exchange of shares of Columbia Financial for shares of Columbia Financial, Inc. and the completion of the Merger with Northfield Bancorp, assuming that 70% of Northfield Bancorp’s outstanding shares of common stock are\nexchanged for shares of Columbia Financial, Inc. common stock and 30% of Northfield Bancorp’s outstanding shares of common stock are exchanged for cash in the Merger. Information is presented at the adjusted minimum, minimum, midpoint and\nmaximum of the offering range. Information presented at the adjusted minimum assumes 41,800,140 shares will be issued as merger consideration.\n\n**Columbia Financial, Inc.**\n**Shares Issued**\n**in the Merger**\n\n**Columbia Financial, Inc.**\n**Shares Sold**\n**in the Offering**\n\n**Columbia Financial, Inc.**\n**Exchange Shares Issuedto Minority Stockholders**\n\n**Columbia Financial, Inc.**\n**Shares Outstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\nAdjusted Minimum\n\n41,800,140\n\n21.46\n%\n\n100,574,860\n\n51.64\n%\n\n52,382,845\n\n26.90\n%\n\n194,757,845\n\n100.00\n%\n\nMinimum\n\n41,800,140\n\n17.67\n%\n\n142,375,000\n\n60.19\n%\n\n52,382,845\n\n22.14\n%\n\n236,557,985\n\n100.00\n%\n\nMidpoint\n\n41,800,140\n\n15.43\n%\n\n167,500,000\n\n61.82\n%\n\n61,626,877\n\n22.75\n%\n\n270,927,017\n\n100.00\n%\n\nMaximum\n\n42,973,477\n\n14.02\n%\n\n192,625,000\n\n62.85\n%\n\n70,870,908\n\n23.12\n%\n\n306,469,385\n\n100.00\n%\n\nThe following table shows the total number of shares of Columbia Financial, Inc. common stock that will be\noutstanding after the completion of the offering, the exchange of shares of Columbia Financial for shares of Columbia Financial, Inc. and the completion of the Merger with Northfield Bancorp, assuming that 100% of Northfield Bancorp’s\noutstanding shares of common stock are exchanged for shares of Columbia Financial, Inc. common stock in the Merger.\n\n20\n\n##### Table of Contents\n\nInformation is presented at the adjusted minimum, minimum, midpoint and maximum of the offering range. Information presented at the adjusted minimum assumes 59,714,485, shares will be issued as\nmerger consideration.\n\n**Columbia Financial, Inc.**\n**Shares Issued**\n**in the Merger**\n\n**Columbia Financial, Inc.**\n**Shares Sold**\n**in the Offering**\n\n**Columbia Financial, Inc.**\n**Exchange Shares Issuedto Minority Stockholders**\n\n**Columbia Financial, Inc.**\n**Shares Outstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\n**Number**\n\n**Percent ofSharesOutstanding**\n\nAdjusted Minimum\n\n59,714,485\n\n30.66\n%\n\n82,660,515\n\n42.44\n%\n\n52,382,845\n\n26.90\n%\n\n194,757,845\n\n100.00\n%\n\nMinimum\n\n59,714,485\n\n23.47\n%\n\n142,375,000\n\n55.95\n%\n\n52,382,845\n\n20.58\n%\n\n254,472,330\n\n100.00\n%\n\nMidpoint\n\n59,714,485\n\n20.67\n%\n\n167,500,000\n\n57.99\n%\n\n61,626,877\n\n21.34\n%\n\n288,841,362\n\n100.00\n%\n\nMaximum\n\n61,390,681\n\n18.90\n%\n\n192,625,000\n\n59.29\n%\n\n70,870,908\n\n21.81\n%\n\n324,886,589\n\n100.00\n%\n\n**How Columbia Financial Determined the Offering Range and Exchange Ratio (page 83)**\n\nFederal regulations require that the aggregate purchase price of the securities sold in the offering be based upon our estimated pro forma\nmarket value after the Conversion (*i.e.*, taking into account the expected receipt of proceeds from the sale of securities in the offering), as determined by an independent appraisal. In accordance with the regulations of the Federal Reserve\nBoard, a valuation range is established that ranges from 15% below to 15% above this pro forma market value. Columbia Financial has retained RP Financial, LC. (“RP Financial”), which is experienced in the evaluation and appraisal of\nfinancial institutions, to prepare the appraisal. RP Financial has indicated that in its valuation as of February 2, 2026, the pro forma market value of Columbia Financial’s common stock (taking into account the acquisition of Northfield\nBancorp) was $2.7 billion, resulting in a range from $2.4 billion at the minimum to $3.1 billion at the maximum. Based on this independent valuation, Columbia Financial, Inc. is selling the number of shares representing the 73.1% of\noutstanding Columbia Financial common stock currently owned by Columbia Bank MHC. This results in an offering range of $1.4 billion to $1.9 billion, with a midpoint of  $1.7 billion. The appraised full conversion value (offering\nshares and exchange shares) ranges from $1.9 billion to $2.6 billion, with the midpoint of $2.291 billion.\n\nRP Financial will receive\nfees totaling $625,000 for its appraisal report, plus $25,000 for any appraisal updates (of which there will be at least one) and reimbursement of out-of-pocket\nexpenses.\n\nIn preparing its appraisal, RP Financial considered the information in this document, including our financial statements. RP\nFinancial also considered the following factors, among others:\n\n•\n\nthe trading market for Columbia Financial common stock and securities of comparable institutions and general\nconditions in the market for such securities;\n\n•\n\nour historical and projected operating results and financial condition and that of Northfield Bancorp, including,\nbut not limited to, net interest income, the amount and volatility of interest income and interest expense relative to changes in market conditions and interest rates, asset quality, levels of loan loss provisions, the amount and sources of non-interest income, and the amount of non-interest expense;\n\n•\n\nthe economic, demographic and competitive characteristics of our post-Merger market area, including, but not\nlimited to, employment by industry type, unemployment trends, size and growth of the population, trends in household and per capita income, and deposit market share;\n\n•\n\na comparative evaluation of our pro forma operating and financial statistics with those of other\nsimilarly-situated, publicly-traded banks and bank holding companies and savings and loan holding companies, which included a comparative analysis of balance sheet composition, income statement and balance sheet ratios, credit and interest rate risk\nexposure; and\n\n•\n\nthe effect of the capital raised in this offering and the effect of our Merger with Northfield Bancorp on our net\nworth and earnings potential, including, but not limited to, the increase in consolidated equity resulting from the offering, the estimated increase in earnings resulting from the investment of the net proceeds of the offering, and the estimated\nimpact on consolidated equity and earnings resulting from adoption of the proposed employee stock benefit plans.\n\nRP\nFinancial considered adjustments to the pro forma market value based on a comparison of Columbia Financial with a peer group of publicly traded bank holding companies and savings and loan holding companies that RP Financial considered comparable to\nColumbia Financial under regulatory guidelines applicable to the independent valuation. Under these guidelines, a minimum of ten peer group companies are selected from the universe of all publicly-traded financial institutions with relatively\ncomparable resources, strategies and financial and other operating\n\n21\n\n##### Table of Contents\n\ncharacteristics. Such companies must also be traded on an exchange (such as Nasdaq or the New York Stock Exchange). The peer group companies selected for Columbia Financial were all\nfully-converted stock institutions or commercial banks that were not subject to an actual or rumored acquisition and that had been in fully-converted form for at least one year. In addition, RP Financial limited the peer group companies to\ninstitutions located in the Mid-Atlantic with assets between $7.0 billion and $25.0 billion, tangible equity-to-assets\nratios of greater than 8.0%, and positive core earnings. The peer group companies included companies with:\n\n•\n\naverage assets of $12.7 billion;\n\n•\n\naverage non-performing assets of 0.54% of total assets;\n\n•\n\naverage loans of 75.7% of total assets;\n\n•\n\naverage tangible equity of 9.0% of total assets; and\n\n•\n\naverage core income of 0.97% of average assets.\n\nThe appraisal was based in part upon the financial condition and results of operations, the effect of the additional capital that will be\nraised from the sale of common stock in this offering and the effect of the Merger and an analysis of a peer group of 12 publicly traded bank and thrift holding companies that RP Financial considered comparable to Columbia Financial. The appraisal\npeer group consists of the companies listed below. Total assets are as of December 31, 2025.\n\n**Company Name and Ticker Symbol**\n\n**Exchange**\n\n**Headquarters**\n\n**Total Assets**\n**(in millions)**\n\nCNB Financial Corp. (CCNE)\n\nNASDAQ\n\nClearfield, PA\n\n$\n8,396\n\nConnectOne Bancorp, Inc. (CNOB)\n\nNASDAQ\n\nEnglewood Cliffs, NJ\n\n$\n14,003\n\nDime Community Bancshares, Inc. (DCOM)\n\nNASDAQ\n\nHauppauge, NY\n\n$\n15,342\n\nFirst Commonwealth Financial Corp. (FCF)\n\nNYSE\n\nIndiana, PA\n\n$\n12,343\n\nKearny Financial Corp. (KRNY)\n\nNASDAQ\n\nFairfield, NJ\n\n$\n7,261\n\nNBT Bancorp, Inc. (NBTB)\n\nNASDAQ\n\nNorwich, NY\n\n$\n15,995\n\nPeapack-Gladstone Financial Corp. (PGC)\n\nNASDAQ\n\nBedminster, NJ\n\n$\n7,526\n\nProvident Financial Services, Inc. (PFS)\n\nNYSE\n\nJersey City, NJ\n\n$\n24,981\n\nS&T Bancorp, Inc. (STBA)\n\nNASDAQ\n\nIndiana, PA\n\n$\n9,871\n\nTompkins Financial Corporation (TMP)\n\nNYSEAM\n\nIthaca, NY\n\n$\n8,668\n\nUnivest Financial Corp. (UVSP)\n\nNASDAQ\n\nSouderton, PA\n\n$\n8,437\n\nWSFS Financial Corp. (WSFS)\n\nNASDAQ\n\nWilmington, DE\n\n$\n21,314\n\nRP Financial considered adjustments to the pro forma market value based on a comparison of Columbia Financial\nwith the peer group. RP Financial advised the board of directors that the valuation analysis took into consideration that relative to the peer group a slight downward adjustment was applied for profitability, growth and viability of earnings.\nAdditionally, RP Financial made slight upward adjustments for Columbia Financial’s financial condition and asset growth in comparison to the peer group’s characteristics for those valuation parameters. RP Financial made no adjustments\nfor primary market area, dividends, liquidity of the shares, marketing of the issue, management and the effect of government regulations and regulatory reform.\n\nThe downward adjustment applied for profitability, growth and viability of earnings took into consideration Columbia Financial’s lower\npro forma core earnings, based on Columbia Financial’s lower pro forma returns on average assets and average equity. The upward adjustment applied for financial condition was due to Columbia Financial’s more favorable credit quality\nmeasures and stronger pro forma capital position. The upward adjustment applied for asset growth was due to Columbia Financial’s stronger pro forma asset growth as the result of the acquisition of Northfield Bancorp and greater leverage\ncapacity as the result of the capital that will be raised in the offering.\n\nFour measures that some investors use to analyze whether a\nstock might be a good investment are the ratios of the offering price to the issuer’s “book value” and “tangible book value” and the ratios of the offering price to the issuer’s earnings and “core\nearnings.” RP Financial considered these ratios in preparing its appraisal, among other factors. Book value is the same as total equity and represents the difference in value between the issuer’s assets and liabilities. Tangible book\nvalue is equal to total equity minus intangible assets. For purposes of the appraisal, core earnings is defined as net earnings after taxes, excluding the after-tax portion of income from non-recurring items.\n\n22\n\n##### Table of Contents\n\nThe following table presents a summary of selected pricing ratios for the peer group\ncompanies utilized by RP Financial in its appraisal and the pro forma pricing ratios for us as calculated by RP Financial in its appraisal report, based on financial data as of and for the twelve months ended December 31, 2025. Stock\nprices are as of February 2, 2026 as reflected in the appraisal report.\n\n**Price toCoreEarningsMultiple(1)**\n\n**Price toBook ValueRatio**\n\n**Price toTangibleBook ValueRatio**\n\nColumbia Financial (pro forma):\n\nAdjusted Minimum\n\n18.30\nx\n\n79.30\n%\n\n85.98\n%\n\nMinimum\n\n20.06\n\n82.24\n\n88.03\n\nMidpoint\n\n22.06\n\n87.03\n\n92.76\n\nMaximum\n\n24.04\n\n91.74\n\n97.28\n\nPeer group companies as of February 2, 2026:\n\nAverage\n\n12.81\nx\n\n107.09\n%\n\n136.39\n%\n\nMedian\n\n12.28\n\n107.53\n\n132.17\n\n(1)\n\nPrice to core earnings multiples calculated by RP Financial in the independent appraisal are based on an\nestimate of  “core” or recurring earnings on a trailing twelve-month basis through December 31, 2025. These ratios are different than presented in “*Pro Forma Data.”*\n\nCompared to the average pricing ratios of the peer group, at the maximum of the offering range, our common stock would be priced at a premium\nof 87.7% to the peer group on a price-to-core earnings basis, a discount of 14.3% to the peer group on a\nprice-to-book basis and a discount of 28.7% to the peer group on a price-to-tangible book\nbasis. This means that, at the maximum of the offering range, a share of our common stock would be more expensive than the peer group on an earnings basis but less expensive than the peer group on a book value basis and a tangible book value basis.\n\nCompared to the average pricing ratios of the peer group, at the minimum of the offering range, our common stock would be priced at a\npremium of 56.6% to the peer group on a price-to-core earnings basis, a discount of 23.2% to the peer group on a price-to-book basis and a discount of 35.5% to the peer group on a price-to-tangible book basis. This means that, at the minimum\nof the offering range, a share of our common stock would be more expensive than the peer group on an earnings basis and less expensive than the peer group on a book value and tangible book value basis.\n\nOur board of directors reviewed RP Financial’s appraisal report, including the methodology and the assumptions used by RP Financial, and\ndetermined that the offering range was reasonable and adequate. Our board of directors has decided to offer the shares for a price of  $10.00 per share. The purchase price of $10.00 per share was determined by us, taking into account, among\nother factors, the market price of our stock before adoption of the Plan of Conversion, the requirement under Federal Reserve Board regulations that the common stock be offered in a manner that will achieve the widest distribution of the stock, and\ndesired liquidity in the common stock after the offering. Based upon the appraised full conversion value and the offering range, each existing stockholder of Columbia Financial will receive between 1.8729 shares and 2.5340 shares of Columbia\nFinancial, Inc. common stock for each current share of Columbia Financial common stock they own, with 2.2035 shares at the midpoint. Based upon this exchange ratio, Columbia Financial, Inc. expects to issue between 52,382,845 shares and 70,870,908\nshares of Columbia Financial, Inc. common stock to the holders of Columbia Financial common stock outstanding immediately before the completion of the Conversion and offering. If Columbia Financial, Inc. does not receive orders for at least\n142,375,000 shares in the subscription and community offerings, then, in Columbia Financial, Inc.’s sole discretion, to complete the offering, up to 41,800,140 of the shares issued to the stockholders of Northfield Bancorp in the community\noffering, assuming 70% of the merger consideration is paid in stock, can be applied to the minimum number of shares required to complete the offering. If Columbia Financial, Inc. applies the 41,800,140 shares issued to the stockholders of\nNorthfield Bancorp, then the minimum number of shares that Columbia Financial, Inc. must sell for cash in the subscription and community offerings is 100,574,860.\n\nBecause of differences in important factors such as operating characteristics, location, financial performance, asset size, capital structure\nand business prospects between us and other institutions that comprise our peer group, you should not rely on these comparative valuation ratios as an indication as to whether or not our common stock is an appropriate investment for you. **The\nindependent appraisal is not intended, and must not be construed, as a recommendation of any kind as to the advisability of purchasing our common stock. The appraisal does not indicate market value. You should not assume or expect that the appraisal\ndescribed above means that our common stock will trade at or above the $10.00 purchase price after the offering.**\n\n23\n\n##### Table of Contents\n\nOur board of directors makes no recommendation of any kind as to the advisability of\npurchasing shares of common stock in the offering.\n\n**How Columbia Financial, Inc. Intends to Use the Proceeds of the Offering (page 168)**\n\nThe following table summarizes how Columbia Financial, Inc. intends to use the proceeds of the offering, based on the sale of shares at the\nadjusted minimum, minimum midpoint and maximum of the offering range. The table below assumes the merger consideration for the acquisition of Northfield Bancorp includes 30% cash with the remainder of the consideration in common stock of Columbia\nFinancial, Inc.\n\n**AdjustedMinimum**\n**142,375,000**\n**Shares at$10.00 pershare(1)**\n\n**Minimum**\n**142,375,000**\n**Shares at$10.00**\n**per share**\n\n**Midpoint**\n**167,500,000**\n**Shares at$10.00**\n**Per share**\n\n**Maximum**\n**192,625,000**\n**Shares at$10.00**\n**per share**\n\n(In thousands)\n\nGross offering proceeds\n\n$\n1,423,750\n\n$\n1,423,750\n\n$\n1,675,000\n\n$\n1,926,250\n\nLess: offering expenses\n\n(39,779\n)\n\n(36,311\n)\n\n(38,623\n)\n\n(43,070\n)\n\nNet offering proceeds\n\n1,383,971\n\n1,387,439\n\n1,636,377\n\n1,883,180\n\nLess: merger shares used to complete the offering\n\n(418,001\n)\n\n— \n\n— \n\n— \n\nNet cash proceeds\n\n965,970\n\n1,387,439\n\n1,636,377\n\n1,883,180\n\nLess:\n\nProceeds contributed to Columbia Bank\n\n(482,985\n)\n\n(693,720\n)\n\n(818,189\n)\n\n(941,590\n)\n\nProceeds used for loan to employee stock ownership plan\n\n(42,713\n)\n\n(42,713\n)\n\n(50,250\n)\n\n(57,788\n)\n\nCash merger consideration\n\n(179,143\n)\n\n(179,143\n)\n\n(179,143\n)\n\n(184,172\n)\n\nProceeds remaining for Columbia Financial, Inc.\n\n$\n261,129\n\n$\n471,863\n\n$\n588,795\n\n$\n699,630\n\n(1)\n\nThe number of shares of Columbia Financial, Inc. sold for cash at the adjusted minimum the offering will vary\ndepending on the amount of the merger consideration that is paid in shares of Columbia Financial, Inc. This column assumes that 70% of the merger consideration will be shares of Columbia Financial, Inc., which would result in 100,574,860 shares that\nwould need to be sold in the offering to satisfy the minimum offering requirement. If instead, 100% of the merger consideration is paid in shares of Columbia Financial, Inc., the number of shares required to be sold for cash to satisfy the minimum\noffering requirement would decrease at the adjusted minimum from 100,574,860 shares to 82,660,515 shares and the resulting net cash proceeds would be less than the amount shown in the table above.\n\nInitially, Columbia Financial, Inc. intends to invest the proceeds of the offering in short-term investments and to fund the cash\nconsideration in the Merger. In the future, Columbia Financial, Inc. may use the funds it retains to invest in securities, pay cash dividends, repurchase shares of its common stock (subject to regulatory restrictions), or for general corporate\npurposes. Columbia Bank intends to use the portion of the proceeds that it receives to fund new loans, to invest in securities or for general corporate purposes. However, Columbia Bank has not allocated specific dollar amounts to any particular area\nof its loan portfolio. The amount of time that it will take to deploy the proceeds of the offering into loans will depend primarily on the level of loan demand. Columbia Financial, Inc. and Columbia Bank may also use the proceeds of the offering to\nacquire other financial services companies or branches or open de novo branches as opportunities arise, primarily in or adjacent to our combined market areas following completion of the Merger, although there are no specific understandings or\nagreements to do so at this time.\n\n**Purchases by Columbia Financial Directors and Executive Officers of Columbia Financial (page 306)**\n\nColumbia Financial expects that its directors and executive officers, together with their associates, will subscribe for approximately 422,500\nshares, which is 0.3% of the shares offered at the midpoint of the offering. Columbia Financial’s directors and executive officers will pay the same $10.00 per share price as everyone else who purchases shares in the offering. Like all of\nColumbia Bank’s depositors, Columbia Financial’s directors and executive officers have subscription rights based on their deposits and, in the event of an oversubscription, their orders will be subject to the allocation provisions set\nforth in the Plan of Conversion. Purchases by Columbia Financial’s directors and executive officers will count towards the minimum number of shares we must sell to close the offering. Following the Conversion and offering, and including shares\nreceived in exchange for shares of Columbia Financial, Columbia\n\n24\n\n##### Table of Contents\n\nFinancial’s directors and executive officers, together with their associates, are expected to own 4.799.406 shares of Columbia Financial, Inc. common stock, which would equal 2.1% of\nColumbia Financial, Inc.’s outstanding shares if 167,500,000 shares are sold at the midpoint of the offering range.\n\n**Market for Columbia\nFinancial, Inc.’s Common Stock (page 171)**\n\nColumbia Financial’s common stock is currently listed on the Nasdaq Global\nSelect Market (“Nasdaq”) under the trading symbol “CLBK.” We expect the shares of Columbia Financial, Inc. common stock will continue to be listed on the Nasdaq under the symbol “CLBK” upon the completion of the\nConversion. Once shares of the common stock begin trading, you may contact a stockbroker to buy or sell shares. Persons purchasing the common stock in the offering may not be able to sell their shares at or above the $10.00 offering price. Brokerage\nfirms typically charge commissions related to the purchase or sale of securities.\n\n**Columbia Financial, Inc.’s Dividend Policy (page 170)**\n\nColumbia Financial has not historically paid dividends to its minority stockholders because of Federal Reserve Board regulations and\npolicies that substantially restrict non-grandfathered mutual holding companies, such as Columbia Bank MHC, from waiving dividends declared by its stock holding company.\n\nAfter the completion of the Conversion and offering, Columbia Financial, Inc. intends to pay cash dividends on a quarterly basis. Initially,\nColumbia Financial, Inc. expects the quarterly dividends to be $0.05 per share, which equals $0.20 per share on an annualized basis and a 2.0% yield based on a price of $10.00 per share. The initial dividend and continued payment of dividends will\ndepend on a number of factors, including Columbia Financial, Inc.’s financial condition and results of operations, tax considerations, capital requirements, alternative uses for capital, the number of shares issued in the offering, industry\nstandards and economic conditions.\n\n**Columbia Financial, Inc. cannot guarantee that it will pay dividends or that, if paid, it will not\nreduce or eliminate dividends in the future. See “****Dividend Policy of Columbia Financial, Inc.****” for additional information.**\n\n**Benefits of the Conversion to Management (page 267)**\n\nColumbia Financial, Inc. will recognize additional compensation expense related to the expanded employee stock ownership plan and the intended\nnew equity incentive plan. The actual expense will depend on the market value of Columbia Financial, Inc.’s common stock and will increase if the value of its common stock increases. As reflected under “*Pro Forma Data,”*\nbased upon assumptions set forth therein, the annual expense related to the employee stock ownership plan and the intended new equity incentive plan would have been $11.7 million for the year ended December 31, 2025 on an after-tax basis, assuming shares had been sold at the maximum of the offering range. If awards under the intended new equity incentive plan are funded from authorized but unissued stock, your ownership interest\nwould be diluted by up to approximately 5.16%. See *“Pro Forma Data”* for an illustration of the effects of each of these plans.\n\n**Employee Stock Ownership Plan.** In connection with Columbia Bank’s reorganization to the mutual holding company structure\nin 2018, Columbia Bank’s employee stock ownership plan purchased 4,542,855 shares of Columbia Financial common stock using funds borrowed from Columbia Financial. As of December 31, 2025, the balance of the loan from Columbia Financial to\nthe employee stock ownership plan was $32.7 million.\n\nColumbia Bank’s existing employee stock ownership plan intends to\npurchase an amount of shares equal to 3.0% of the shares sold in the offering. The plan will use the proceeds from a 25**-**year loan from Columbia Financial, Inc. to purchase these shares. Columbia Financial, Inc. may purchase shares of common\nstock in the open market following the offering to fund all or a portion of the intended purchases, subject to Federal Reserve Board approval. As the loan is repaid and shares are released from collateral, the shares will be allocated to the\naccounts of employee participants based on an individual’s compensation as a percentage of total plan compensation. Non-employee directors are not eligible to participate in the plan. Columbia Financial,\nInc. will incur additional compensation expense as a result of this plan. See “*Pro Forma Data”* for an illustration of the effects of this plan.\n\n**New Equity Incentive Plan.** Columbia Financial, Inc. intends to implement a new equity incentive plan no earlier than six months\nafter completion of the Conversion and offering. We will submit this plan to our stockholders for their approval. Under this plan, we may grant stock options in an amount up to 6.20% of the number of shares sold in the offering and restricted stock\nawards or restricted stock units in an amount up to 2.45% of the shares sold in the offering. Stock options will be granted at an exercise price equal to 100% of the fair market value of our common stock\n\n25\n\n##### Table of Contents\n\non the option grant date. Shares of restricted stock and/or restricted stock units will be awarded at no cost to the recipient. We will incur additional compensation expense as a result of\nthis plan. See *“Pro Forma Data”* for an illustration of the effects of this plan. The new equity incentive plan may award a greater number of options and restricted stock if the plan is adopted after one year from the date of the\ncompletion of the Conversion. We have not yet determined the number of shares that would be reserved for issuance under this plan. The new equity incentive plan will comply with all applicable Federal Reserve Board regulations.\n\nThe following table summarizes, at the maximum of the offering range, the total number and value of the shares of common stock that the\nemployee stock ownership plan expects to acquire and the total value of all restricted stock awards/restricted stock units and stock options that are expected to be available under the new equity incentive plan (assuming the equity incentive plan is\nimplemented within one year following the completion of the Conversion).\n\n**Number of Shares to be Granted or Purchased**\n\n**At theMaximum ofthe OfferingRange(1)**\n\n**As aPercentage ofCommon Stockto be Issued inthe Offering**\n\n**Dilution Resultingfrom the Issuanceof Shares forStock BenefitPlans**\n\n**TotalEstimatedValue atMaximum ofOffering Range**\n**(in thousands)**\n\nEmployee stock ownership plan(2)\n\n5,778,750\n\n3.00\n%\n\nNM\n\n$\n57,788\n\nRestricted stock(3)\n\n4,719,313\n\n2.45\n\n1.52\n%\n\n$\n47,193\n\nStock options(4)\n\n11,942,750\n\n6.20\n\n3.75\n%\n\n$\n41,441\n\nTotal\n\n22,440,813\n\n11.65\n%\n\n5.16\n%\n\n$\n146,422\n\n(1)\n\nAt the maximum of the offering range, Columbia Financial, Inc. will sell 192,625,000 shares.\n\n(2)\n\nNo dilution is reflected for the employee stock ownership plan because these shares are assumed to be purchased\nin the offering at the offering price of $10.00 per share.\n\n(3)\n\nThe actual value of restricted stock awards will be determined based on their fair market value as of the date\ngrants are made. For purposes of this table, fair value for stock awards is assumed to be the same as the offering price of $10.00.\n\n(4)\n\nAssumes the value of a stock option is $3.20, which was determined using the Black-Scholes option pricing\nformula. See *“Pro Forma Data.”*\n\nColumbia Financial, Inc. intends to fund its plans through open\nmarket purchases, as opposed to new issuances of authorized common stock. Federal Reserve Board regulations do not permit Columbia Financial, Inc. to repurchase its shares during the first year following the completion of this offering except to\nfund the grants of restricted stock under the stock-based incentive plan or, with prior regulatory approval, under extraordinary circumstances.\n\nThe following table presents information regarding Columbia Bank’s existing employee stock ownership plan and additional shares to be\npurchased by Columbia Bank’s employee stock ownership plan. The table below assumes that 306,469,385 shares are outstanding after the offering, and the Merger, which includes the sale of 192,625,000 shares in the offering at the maximum of the\noffering range, the issuance of 70,870,908 shares in exchange for shares of Columbia Financial using an exchange ratio of 2.5340 and the issuance of 42,973,477 shares to Northfield Bancorp stockholders in the Merger. It is also assumed that the\nvalue of the stock is $10.00 per share.\n\n**EligibleParticipants**\n\n**Number ofShares atMaximum**\n**of OfferingRange**\n\n**EstimatedValue of Shares**\n\n**Percentageof SharesOutstandingafter theConversionandOffering**\n\nEmployees\n\nEmployee Stock Ownership Plan:\n\nShares purchased in 2018 offering(1)\n\n11,511,595\n\n$\n115,115,950\n\n3.76\n%\n\nShares to be purchased in this offering\n\n5,778,750\n\n57,787,500\n\n1.89\n\nTotal\n\n17,290,345\n\n$\n172,903,450\n\n5.64\n%\n\n(1)\n\nRepresents 4,542,855 shares purchased in Columbia Financial’s 2018 minority stock offering, as adjusted\nfor the 2.5340 exchange ratio at the maximum of the offering range. As of December 31, 2025, approximately 1,511,000 of these shares had been allocated to the accounts of participants and approximately 2,793,000 shares remain unallocated.\n\n26\n\n##### Table of Contents\n\n**Dissenters’ Rights (page 93)**\n\nStockholders of Columbia Financial do not have dissenters’ rights in connection with the Conversion and offering.\n\n**Differences in Stockholder Rights (page 315)**\n\nAs a result of the Conversion, existing stockholders of Columbia Financial will become stockholders of Columbia Financial, Inc. The rights of\nstockholders of Columbia Financial, Inc. will be less than the rights stockholders currently have. The decrease in stockholder rights results from differences between the articles of incorporation and bylaws of Columbia Financial, Inc. and the\narticles of incorporation and bylaws of Columbia Financial and from distinctions between Maryland and Delaware law. The differences in stockholder rights under the articles of incorporation and bylaws of Columbia Financial, Inc. are not mandated by\nMaryland law but have been chosen by the board of directors of Columbia Financial, Inc. as being in the best interests of the corporation and all of its stockholders. However, the provisions in Columbia Financial, Inc.’s articles of\nincorporation and bylaws may make it more difficult to pursue a takeover attempt that management opposes. These provisions will also make the removal of the board of directors or management, or the appointment of new directors, more difficult.\n\nThe differences in stockholder rights include the following:\n\n•\n\nsuper-majority voting requirements for certain business combinations and changes to some provisions of the\narticles of incorporation and bylaws;\n\n•\n\nlimitations on the right to vote shares;\n\n•\n\na majority of stockholders required to call special meetings of stockholders; and\n\n•\n\ngreater lead time required for stockholders to submit business proposals or director nominations.\n\n**Tax Consequences (page 90)**\n\nAs a general matter, for U.S. federal and state income tax purposes, the Conversion is not expected to be a taxable transaction to\n(i) Columbia Financial, Inc., (ii) existing stockholders of Columbia Financial that receive Columbia Financial, Inc. common stock in exchange for their Columbia Financial common stock or (iii) persons that receive or exercise subscription\nrights. Existing stockholders of Columbia Financial that receive cash in lieu of a fractional share interest in Columbia Financial, Inc. are expected to recognize gain or loss equal to the difference between the cash received and the tax basis of\nthe fractional share. Kilpatrick Townsend & Stockton LLP and Crowe LLP are expected to issue us opinions to this effect, which are summarized under “*Description of the Plan of\nConversion** **—** **Material U.S. Income Tax Consequences of the Conversion.”*\n\n**The\nMerger**\n\n**The Merger and the Merger Agreement (page 94)**\n\nThe merger of Northfield Bancorp with and into Columbia Financial, Inc. is governed by the Merger Agreement. The Merger Agreement provides that\nif all of the conditions are satisfied or waived, Northfield Bancorp will merge with and into Columbia Financial, Inc., with Columbia Financial, Inc. continuing as the surviving corporation.**** Immediately following the Merger, Northfield\nBank, the wholly owned subsidiary of Northfield Bancorp, will merge with and into Columbia Bank, the wholly owned subsidiary of Columbia Financial, Inc., with Columbia Bank continuing as the surviving institution (the “Bank Merger”). The\ncompletion of the Merger is subject to the completion of the Conversion and the satisfaction of other closing conditions. **We encourage you to read the Merger Agreement in its entirety, which is included as******** Annex\nA******** to this document.**\n\n**Merger Consideration (page 94)**\n\nIf the Merger is completed, each share of Northfield Bancorp’s common stock, par value $0.01 per share, issued and outstanding\nimmediately prior to the effective time of the Merger, will be converted, at the election of the holder, into the right to receive either shares of Columbia Financial, Inc. common stock or cash, as follows: (i) if the Final Independent\nValuation of Columbia Financial, is less than $2.3 billion, 1.425 shares of Columbia Financial, Inc. common stock or $14.25 in cash; (ii) if the Final Independent Valuation of Columbia Financial, Inc. is equal to or greater than\n$2.3 billion and less than $2.6 billion, the Merger Exchange Ratio will be increased to 1.450 shares of Columbia Financial, Inc. common stock and the Per Share Cash Consideration will be increased to $14.50; or (iii) if the Final\nIndependent Valuation of Columbia Financial, Inc. is greater than $2.6 billion, the Merger Exchange Ratio\n\n27\n\n##### Table of Contents\n\nwill be increased to 1.465 shares of Columbia Financial, Inc. and the Per Share Cash Consideration will be increased to $14.65. The “Final Independent Valuation” is also sometimes\nreferred to herein as the “appraised full conversion value.” No more than 30% of the shares of Northfield Bancorp common stock issued and outstanding as of the effective time of the Merger (excluding shares of Northfield Bancorp common\nstock to be canceled as provided the Merger Agreement) will be converted into the aggregate cash consideration. As of the date of this document, the current appraised full conversion value of Columbia Financial, Inc. is $2.291 billion at the\nmidpoint of the offering range.\n\n**Market Price and Share Information (page 171)**\n\nThe following table shows the closing price per share of Columbia Financial common stock, the closing price per share of Northfield Bancorp\ncommon stock and the equivalent price per share of Northfield Bancorp common stock, giving effect to the Merger, on January 30, 2026, which is the last day on which shares of each of Columbia Financial common stock and Northfield Bancorp common\nstock traded preceding the public announcement of the proposed Merger, and on April 30, 2026, the most recent practicable date before the mailing of this document. The implied value of one share of Northfield Bancorp common stock is computed by\nmultiplying the price of a share of Northfield Bancorp common stock by a Merger Exchange Ratio of 1.425. See “*Description of the Merger** **—** **Consideration to be Received in the\nMerger*.”\n\n**Columbia FinancialCommon Stock**\n\n**Northfield Bancorp**\n**Common Stock**\n\n**Implied Value ofOne Share ofNorthfield Bancorp**\n**Common Stock**\n\nJanuary 30, 2026\n\n$\n16.27\n\n$\n12.32\n\n$\n14.25\n\nApril 30, 2026\n\n$\n19.23\n\n$\n13.95\n\n$\n14.25\n\n**Treatment of Northfield Bancorp Equity Awards (page 130)**\n\nImmediately prior to the effective time of the Merger, each outstanding unvested share of Northfield Bancorp Restricted Stock that is subject\nto time-based vesting will fully vest and be treated as an issued and outstanding share of Northfield Bancorp common stock for purposes of receiving the merger consideration set forth in the Merger Agreement. Additionally, (i) immediately prior\nto the effective time of the Merger, each outstanding unvested Northfield Bancorp PSRU will fully vest, with any applicable performance-based vesting condition to be deemed achieved at the greater of the target level of performance or actual\nannualized performance measured as of the most recent completed fiscal quarter, and will be treated as an issued and outstanding share of Northfield Bancorp common stock for purposes of receiving the merger consideration set forth in the Merger\nAgreement, and (ii) in connection with the Merger, Northfield Bancorp granted cash-settled restricted stock units (the “Northfield Bancorp Cash-Settled RSUs”). The grants of Northfield Bancorp Cash-Settled RSUs to executives are\nsubject to a three-year vesting schedule, with the awards vesting ratably each year, grants to non-employee directors are subject to a one-year cliff vesting schedule,\nand in the event of a termination without cause, a termination for good reason, death or disability prior to February 4, 2027, the awards that are scheduled to otherwise vest on February 4, 2027 will automatically vest. Columbia Financial,\nInc. will not assume any Northfield Bancorp Restricted Stock or Northfield Bancorp PSRUs in connection with the Merger.\n\nAt the effective\ntime of the Merger, each outstanding Northfield Bancorp stock option, whether vested or unvested, will fully vest and be converted automatically into an option to purchase shares of Columbia Financial, Inc. common stock and will continue to be\nsubject to the same terms and conditions as applied to the Northfield Bancorp stock option immediately prior to the effective time of the Merger. The number of shares of Columbia Financial, Inc. common stock subject to each assumed Northfield\nBancorp stock option will be equal to the number of shares of Northfield Bancorp common stock subject to the stock option immediately prior to the effective time of the Merger, multiplied by the Merger Exchange Ratio and rounded down to the nearest\nwhole share. The per share exercise price of each assumed Northfield Bancorp stock option will also be adjusted by dividing the per share exercise price of the stock option by the Merger Exchange Ratio, rounded up to the nearest cent.\n\n**Columbia Financial’s Reasons for the Merger; Recommendation of the Columbia Financial Board of Directors (page 115)**\n\n**The Columbia Financial board of directors has unanimously (i)******** determined that the Merger Agreement and the Merger\ncontemplated thereby are in the best interest of Columbia Financial and its stockholders and (ii)******** approved the Merger Agreement and the consummation of the transactions contemplated thereby, including the issuance of shares of\nColumbia Financial, Inc. common stock as merger consideration, as well as the**\n\n28\n\n##### Table of Contents\n\n**Conversion. The Columbia Financial board of directors unanimously recommends that Columbia Financial stockholders vote “FOR” the Columbia Conversion Proposal, “FOR” the\nColumbia Merger Proposal, and “FOR” the Columbia Adjournment Proposal, if necessary.**In reaching this decision, Columbia Financial’s board of directors considered a variety of factors, which are described in the section\nentitled “*Description of the Merger—Columbia Financial’s Reasons for the Merger*;* Recommendation of Columbia Financial’s Board of Directors*.” Completion of the Merger is conditioned upon approval by\nColumbia Financial stockholders of the Columbia Conversion Proposal and the Columbia Merger Proposal. Completion of the Merger is not conditioned upon approval of the Columbia Adjournment Proposal or the other matters to be voted upon at the\nColumbia Financial Annual Meeting.\n\nIn addition, the Columbia Financial board of directors recommends that Columbia Financial stockholders\nvot**e**“FOR” the Columbia Super-Majority Proposal, “FOR” the Columbia 10% Beneficial Owner Proposal, “FOR” the Columbia Director Election Proposal, “FOR” the Columbia Auditor Ratification\nProposal, “FOR” the Columbia Say-on-Pay Proposal and for “ONE YEAR” for the Columbia Say-on-Pay Frequency Proposal.****\n\n**Northfield Bancorp’s Reasons for the Merger; Recommendation of\nthe Northfield Bancorp Board of Directors (page 106)**\n\n**The Northfield Bancorp board of directors has unanimously\n(i)******** determined that the Merger Agreement and the Merger contemplated thereby is in the best interest of Northfield Bancorp and its stockholders, and (ii)******** approved and declared advisable the Merger Agreement, the\nMerger, and the other actions contemplated by the Merger Agreement. The Northfield Bancorp board of directors unanimously recommends that Northfield Bancorp stockholders vote “FOR” the Northfield Merger Proposal, “FOR” the\nNorthfield Merger-Related Compensation Proposal, and “FOR” the Northfield Adjournment Proposal, if necessary.**In reaching this decision, Northfield Bancorp’s board of directors considered a variety of factors, which are\ndescribed in the section entitled “*Description of the Merger—Northfield Bancorp’s Reasons for the Merger; Recommendation of the Northfield Bancorp’s Board of Directors*.” Completion of the Merger is conditioned\nupon approval by Northfield Bancorp stockholders of the Northfield Merger Proposal. Completion of the Merger is not conditioned upon approval of the Northfield Merger-Related Compensation Proposal or the Northfield Adjournment Proposal.\n\n**Opinion of Columbia Financial’s Financial Advisor (page 117)**\n\nIn connection with the Merger, Keefe, Bruyette & Woods, Inc. (“KBW”), as financial advisor to Columbia Financial in\nconnection with the Merger, delivered a written opinion, dated January 31, 2026, to the Columbia Financial board of directors as to the fairness, from a financial point of view and as of the date of the opinion, to Columbia Financial, Inc. of\nthe aggregate merger consideration in the Merger. The full text of KBW’s opinion, which describes the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by KBW in preparing\nthe opinion, is attached as *Annex B* to this Joint Proxy Statement/Prospectus.\n\n*The opinion was for the information of, and was\ndirected to, the Columbia Financial board of directors (in its capacity as such) in connection with its consideration of the financial terms of the Merger. The opinion did not address the underlying business decision of Columbia Financial to engage\nin the Merger or enter into the Merger Agreement or constitute a recommendation to the Columbia Financial board of directors in connection with the Merger, and it does not constitute a recommendation to any stockholder of Columbia Financial or any\nother entity as to how to vote or act in connection with the Merger or any other matter (including, with respect to holders of Northfield Bancorp common stock, what election any such stockholder should make with respect to the Merger Exchange Ratio\nor the Per Share Cash Consideration).*\n\n**Opinion of Northfield Bancorp’s Financial Advisor (page 109)**\n\nAt the January 31, 2026 meeting of the Northfield Bancorp board of directors, representatives of Raymond James & Associates, Inc.\n(“Raymond James”) rendered Raymond James’s opinion, subsequently confirmed in writing and dated January 31, 2026, to the Northfield Bancorp board of directors (in its capacity as such), as to the fairness, as of such date,\nfrom a financial point of view, to the Northfield Bancorp stockholders of the consideration to be received by such holders in the Merger pursuant to the Merger Agreement, based upon and subject to the assumptions made, procedures followed, matters\nconsidered and qualifications and limitations on the scope of the review undertaken by Raymond James in connection with the preparation of its opinion.\n\n29\n\n##### Table of Contents\n\nThe full text of the written opinion of Raymond James, dated January 31, 2026, which\nsets forth, among other things, the various assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of the review undertaken by Raymond James, is attached as *Annex C to this Joint Proxy\nStatement/Prospectus. Raymond James provided its opinion for the information and assistance of the Northfield Bancorp board of directors (in its capacity as such) in connection with, and for purposes of, its consideration of the financial terms of\nthe Merger and its opinion only addresses whether the consideration to be received by the Northfield Bancorp stockholders in the Merger pursuant to the Merger Agreement was fair, from a financial point of view, to such holders as of the date of the\nRaymond James opinion. The opinion of Raymond James did not address any other term or aspect of the Merger Agreement or the transactions contemplated thereby, the underlying business decision of Northfield Bancorp to engage in the Merger, the form\nor structure of the Merger, the relative merits of the Merger as compared to any other alternative business strategies that might exist for Northfield Bancorp, or any other transaction in which Northfield Bancorp might engage.*\n\n*The summary of the opinion is qualified in its entirety by reference to the full text of the opinion. Northfield Bancorp stockholders are\nurged to read the entire opinion carefully in connection with their consideration of the Merger Agreement and the Merger. Neither the Raymond James opinion nor the summary of its opinion and the related analyses set forth in this Joint Proxy\nStatement/Prospectus is intended to be or constitute advice or a recommendation to the Northfield Bancorp board of directors or any Northfield Bancorp stockholder as to how the Northfield Bancorp board of directors, such stockholder or any other\nperson should vote or otherwise act with respect to the Merger or any other matter. The opinion of Raymond James speaks only as of the date of the opinion and does not reflect any developments that may occur or may have occurred after the date of\nits opinion and prior to the completion of the Merger.*\n\n**Directors and Executive Officers of the Surviving Corporation (page 140)**\n\n**Board of Directors.**Prior to the effective time of the Merger, Columbia Financial, Inc. will increase the full board of directors\nof the surviving corporation at the effective time by four members (for a total of 13 directors). As of the effective time of the Merger, the board of directors of Columbia Financial, Inc. will be comprised of nine Columbia Financial directors and\nfour members of the Northfield Bancorp board of directors selected by Columbia Financial, one of whom shall be Steven M. Klein.****In addition, effective as of the effective time of the Bank Merger, each of the four Northfield Bancorp\ndirectors appointed to the Columbia Financial, Inc. board of directors will also be appointed to the Columbia Bank board of directors. Each director of Northfield Bancorp who is appointed to the boards of directors of Columbia Financial, Inc. and\nColumbia Bank will serve on each such board of directors for at least four years from the effective time of the Merger.\n\n**Executive\nOfficers.**Following the completion of the Merger and the Bank Merger, the executive officers of Columbia Financial, Inc. and Columbia Bank will continue in office in the positions in which they served immediately prior to the effective time\nof the Merger. In addition, upon the effective time of the Merger, Steven M. Klein, the President and Chief Executive Officer of Northfield Bancorp and Northfield Bank, will be appointed as Senior Executive Vice President and Chief Operating Officer\nof Columbia Financial, Inc. and Columbia Bank.\n\nFor a more information, see “*Description of the Merger—Directors and\nExecutive Officers of the Surviving Corporation.*”\n\n**Interests of Columbia Financial’s Directors and Executive Officers in the Merger\n(page 134)**\n\nIn considering the recommendation of the board of directors of Columbia Financial to approve the Merger Agreement, you\nshould be aware that Columbia Financial’s directors and executive officers have interests in the Merger that are different from, or in addition to, the interests of Columbia Financial stockholders generally and that may create potential\nconflicts of interest. The board of directors of Columbia Financial was aware of these interests and considered them, among other matters, in approving the Merger Agreement and related transactions. These interests include that nine Columbia\nFinancial directors will continue to serve on the board of directors of Columbia Financial, Inc. and Columbia Bank following the effective time of the Merger, as further described in “*Description of the Merger—Interests of Columbia\nFinancial’s Directors and Executive Officers in the Merger*.”\n\n**Interests of Northfield Bancorp’s Directors and Executive Officers\nin the Merger (page 134)**\n\nIn considering the recommendation of the board of directors of Northfield Bancorp to approve the Merger\nAgreement, you should be aware that Northfield Bancorp’s directors and executive officers have employment and other compensation agreements or plans that give them financial interests in the Merger that are different from, or in addition to,\nthe interests of Northfield Bancorp stockholders generally and that may create potential conflicts of\n\n30\n\n##### Table of Contents\n\ninterest. The board of directors of Northfield Bancorp was aware of these interests and considered them, among other matters, in approving the Merger Agreement and related transactions. These\ninterests include:\n\n•\n\nNorthfield Bank has entered into settlement agreements with each of Steven M. Klein, William R. Jacobs,\nDavid V. Fasanella, Robin Lefkowitz and Vickie Tomasello, pursuant to which each executive’s employment agreement with Northfield Bank will be terminated as of the effective time of the Merger in exchange for a lump sum payment to be made at\nthe closing of the Merger;\n\n•\n\nColumbia Financial, Inc. and Columbia Bank have entered into an employment agreement with\nSteven M. Klein, to be effective as of the effective time of the Merger, in connection with his appointment as Senior Executive Vice President and Chief Operating Officer of Columbia Financial, Inc. and Columbia Bank following the\ncompletion of the Merger and the Bank Merger;\n\n•\n\nIn connection with the Merger, Northfield Bancorp granted the Northfield Bancorp Cash-Settled RSUs on\nFebruary 4, 2026. The Northfield Bancorp Grants of Cash-Settled RSUs to executives are subject to a three-year vesting schedule, with the awards vesting ratably each year, grants to non-employee directors\nare subject to a one-year cliff vesting schedule, and in the event of a termination without cause, a termination for good reason, death or disability prior to February 4, 2027, the awards that are\nscheduled to otherwise vest on February 4, 2027 will automatically vest;\n\n•\n\nEach outstanding unvested share of Northfield Bancorp Restricted Stock that is subject to time-based vesting will\nbecome fully vested at closing of the Merger and will be treated as an issued and outstanding share of Northfield Bancorp common stock for purposes of receiving the merger consideration set forth in the Merger Agreement;\n\n•\n\nEach outstanding unvested Northfield Bancorp PSRU will fully vest at the closing of the Merger, with any\napplicable performance-based vesting condition to be deemed achieved at the greater of the target level of performance or actual annualized performance measured as of the most recent completed fiscal quarter, and will be treated as an issued and\noutstanding share of Northfield Bancorp common stock for purposes of receiving the merger consideration set forth in the Merger Agreement;\n\n•\n\nAt the effective time of the Merger, each outstanding Northfield Bancorp stock option, whether vested or\nunvested, will fully vest and be converted automatically into an option to purchase shares of Columbia Financial, Inc. common stock, as adjusted for the Merger Exchange Ratio, as set forth in the Merger Agreement;\n\n•\n\nAt the effective time of the Merger, four Northfield Bancorp directors, including Steven M. Klein, will be\nappointed to the boards of directors of Columbia Financial, Inc. and Columbia Bank; and\n\n•\n\nNorthfield Bancorp’s directors and executive officers are entitled to continued indemnification and\ninsurance coverage under the Merger Agreement.\n\nFor a more complete description of these interests, see\n“*Description of the Merger—Interests of Northfield Bancorp’s Directors and Executive Officers in the Merger*.”\n\n**Regulatory Approvals (page 134)**\n\nSubject\nto the terms of the Merger Agreement, the parties have agreed to cooperate with each other and use their reasonable best efforts to promptly prepare and file all necessary documentation, to effect all applications, notices, petitions and filings, to\nobtain as promptly as practicable all permits, consents, approvals and authorizations of all third parties and governmental entities which are necessary or advisable to consummate the transactions contemplated by the Merger Agreement (including the\nMerger and the Bank Merger), and to comply with the terms and conditions of all such permits, consents, approvals and authorizations of all such governmental entities. The requisite regulatory approvals include, among other things, the approval of\nthe Board of Governors of the Federal Reserve System (the “Federal Reserve Board”) for the Merger and the approval of the OCC for the Bank Merger. The completion of the Merger is also subject to the completion of the Conversion, which\nmust be approved by the Federal Reserve Board. Columbia Financial, Columbia Bank MHC and Columbia Financial, Inc. have filed the required applications for approval of the Merger and the Conversion with the Federal Reserve Board and Columbia Bank has\nfiled the required application for approval of the Bank Merger with the OCC. As of the date of this joint proxy statement/prospectus, (i) the Federal Reserve Board has conditionally approved the Conversion and offering and (ii) the Federal\nReserve Board and the OCC have conditionally approved the Merger and the Bank Merger, respectively.\n\n31\n\n##### Table of Contents\n\n**Conditions to Completing the Merger (page 148)**\n\nThe completion of the Merger is subject to the fulfillment of a number of closing conditions, including:\n\n•\n\nthe completion of the Conversion (including the approval of the Conversion by the stockholders of Columbia\nFinancial and by the members of Columbia Bank MHC);\n\n•\n\nthe approval of the Merger Agreement by the stockholders of each of Columbia Financial and Northfield Bancorp;\n\n•\n\nthe authorization for listing on the Nasdaq Global Select Market of the shares of Columbia Financial, Inc. common\nstock that will be issued as merger consideration;\n\n•\n\nthe receipt or provision of all non-governmental notices, consents or\nwaivers by non-governmental third parties, except as would not reasonably be expected to have a material adverse effect on Columbia Financial, Columbia Financial, Inc. or Northfield Bancorp;\n\n•\n\nthe effectiveness of the Registration Statement on Form S-4 of which this\nJoint Proxy Statement/Prospectus is a part, and the absence of any stop order by the SEC suspending such effectiveness;\n\n•\n\nthe receipt of all required regulatory approvals, in each case without the imposition of any materially\nburdensome regulatory condition (which we have conditionally received);\n\n•\n\nno order, injunction or decree issued by any court or governmental entity or other legal restraint or prohibition\npreventing the completion of the Merger or the Bank Merger;\n\n•\n\nthe deposit of cash and certificates representing sufficient shares of Columbia Financial, Inc. common stock\nsufficient to pay the merger consideration;\n\n•\n\nthe absence of any event that, individually or in the aggregate, has had or will reasonably be likely to have a\nmaterial adverse effect on Northfield Bancorp or any of its subsidiaries;\n\n•\n\nthe accuracy of the representations and warranties of the Columbia Parties and Northfield Bancorp contained in\nthe Merger Agreement, both as of the date of the Merger Agreement and as of the closing of the Merger, subject to the materiality standards provided for in the Merger Agreement;\n\n•\n\nthe performance in all material respects by each of the Columbia Parties and Northfield Bancorp of their\nrespective obligations, covenants and agreements required to be performed under the Merger Agreement; and\n\n•\n\nthe receipt by each of the parties of an opinion of legal counsel that the Merger will qualify as a\n“reorganization” within the meaning of Section 368(a) of the Code.\n\n**Terminating the Merger Agreement (page 148)**\n\nThe Merger Agreement may be terminated by mutual written consent of Columbia Financial and Northfield Bancorp at any time prior to the\ncompletion of the Merger. Additionally, subject to conditions and circumstances described in the Merger Agreement, either Columbia Financial or Northfield Bancorp may terminate the Merger Agreement as follows:\n\n•\n\nby either party (i) for failure to receive any required regulatory approval, (ii) if the Merger has not\nbeen completed by January 31, 2027; (iii) if the other party breaches its representations, warranties or obligations under the Merger Agreement and the breach that cannot be cured, in all cases if the party seeking to terminate the Merger\nAgreement is not responsible for the circumstances giving rise to termination;\n\n•\n\nby either party, if the Merger is not approved by either of Columbia Financial’s or Northfield\nBancorp’s stockholders;\n\n•\n\nby Columbia Financial, if, prior to the receipt of Northfield Bancorp stockholder approval, (i) Northfield\nBancorp or the Northfield Bancorp board of directors withholds, withdraws, modifies or qualifies its recommendation in favor of the Northfield Merger Proposal or (ii) Northfield Bancorp or the Northfield Bancorp board of directors breaches in\nany material respect its obligations related to calling, giving notice of, and commencing the Northfield Bancorp stockholder meeting or its “no-shop” obligations related to third party acquisition\nproposals under the Merger Agreement;\n\n•\n\nby Northfield Bancorp if, prior to the receipt of Columbia Financial stockholder approval, (i) Columbia\nFinancial or the Columbia Financial board of directors withholds, withdraws, modifies or qualifies its recommendation in favor of the Columbia Merger Proposal or (ii) Columbia Financial or the Columbia Financial board of directors breaches in\nany material respect its obligations related to calling, giving notice of, and commencing the Columbia Financial stockholder meeting;\n\n32\n\n##### Table of Contents\n\n•\n\nby either party, if Columbia Financial is unable to complete the Conversion on or before January 31, 2027;\nor\n\n•\n\nby Northfield Bancorp or Columbia Financial, if (i) the midpoint of the valuation range included in the\nFinal Independent Valuation has decreased by 20% or more from the preliminary midpoint of the valuation range (the “Preliminary Midpoint”) provided by the independent appraiser at the time of the first public announcement of the Merger\nand (ii) Columbia Financial and Northfield Bancorp are unable to agree on a mutually acceptable adjustment to the amount of the merger consideration taking into account such decrease from the Preliminary Midpoint.\n\n**Termination Fee (page 149)**\n\nIf the Merger\nAgreement is terminated under certain circumstances, a termination fee of $23.7 million will be payable by either Northfield Bancorp or Columbia Financial, as applicable. In addition, if the Merger Agreement is terminated under certain other\ncircumstances, a termination fee of $6.0 million will be payable by Columbia Financial. See “*Description of the Merger—* *Termination Fee*” for a description of the circumstances under which a termination fee is\npayable. The termination fee could discourage other companies from seeking to acquire either Northfield Bancorp or Columbia Financial.\n\n**Support\nAgreements (page 149)**\n\nConcurrently with the execution and delivery of the Merger Agreement, each of the members of the board of\ndirectors of Northfield Bancorp entered into a support agreement pursuant to which, among other things, each of the members of the board of directors of Northfield Bancorp agreed, subject to the terms of the support agreement, to (i) vote the\nshares of Northfield Bancorp common stock over which he or she has the sole power to vote or direct the voting of in favor of the approval of the Northfield Merger Proposal, and against any competing transaction and (ii) not transfer any such\nshares of Northfield Bancorp common stock prior to the Northfield Bancorp Special Meeting, with certain limited exceptions. The support agreements will terminate upon the earlier of the termination of the Merger Agreement or the effective time. As\nof April 27, 2026, the record date for the Northfield Bancorp Special Meeting, the members of the board of directors of Northfield Bancorp owned and held the sole dispositive and voting power over shares of Northfield Bancorp common stock\nrepresenting approximately 4.0% of the voting power represented by all issued and outstanding shares of Northfield Bancorp common stock. A copy of the support agreement is included as an exhibit to the Merger Agreement, which is included\nas* Annex**** A* to this Joint Proxy Statement/Prospectus.\n\nIn addition, concurrently with the execution and\ndelivery of the Merger Agreement, each of the members of the board of directors of Columbia Financial entered into a support agreement pursuant to which, among other things, each of the members of the board of directors of Columbia Financial agreed,\nsubject to the terms of the support agreement, to (i) vote the shares of Columbia Financial common stock over which he or she has the sole power to vote or direct the voting of in favor of the approval of the Columbia Merger Proposal, and\nagainst any competing transaction, and in favor of the approval of the Columbia Conversion Proposal and (ii) not transfer any such shares of Columbia Financial common stock prior to the Columbia Financial Annual Meeting, with certain limited\nexceptions. The support agreements will terminate upon the earlier of the termination of the Merger Agreement or the effective time. As of April 30, 2026, the record date for the Columbia Financial Annual Meeting, the members of the board of\ndirectors of Columbia Financial owned and held the sole dispositive and voting power over shares of Columbia Financial common stock representing approximately 1.1% of the voting power represented by all issued and outstanding shares of Columbia\nFinancial common stock. A copy of the support agreement is included as an exhibit to the Merger Agreement, which is included as* Annex**** A* to this Joint Proxy Statement/Prospectus.\n\n**Comparison of Rights of Northfield Bancorp and Columbia Financial, Inc. Stockholders (page 322)**\n\nUpon the completion of the Merger, holders of Northfield Bancorp common stock who receive shares of Columbia Financial, Inc. common stock as\nmerger consideration will become holders of Columbia Financial, Inc. common stock and their rights as stockholders will be governed by Maryland law and the governing documents of Columbia Financial, Inc. The rights of Northfield Bancorp stockholders\nwill change as a result of the Merger due to differences in Columbia Financial’s and Northfield Bancorp’s governing law and documents. See “*Comparison of Stockholders Rights of Columbia Financial, Inc. and Northfield\nBancorp*” for a summary of the material differences between the respective rights of Columbia Financial, Inc. stockholders and Northfield Bancorp stockholders.\n\n33\n\n##### Table of Contents\n\n**Dissenters’ Appraisal Rights (page 150)**\n\nUnder Section 262 of the Delaware General Corporation Law, holders of shares of Northfield Bancorp common stock have the right to obtain\nan appraisal of the value of their shares of Northfield Bancorp common stock in connection with the Merger. To perfect appraisal rights, a Northfield Bancorp stockholder must not vote for the approval of the Merger Agreement and must strictly comply\nwith all of the procedures required under Delaware law. Failure to strictly comply with Section 262 of the Delaware General Corporation Law may result in termination or waiver of appraisal rights. See “*Description of the\nMerger—Dissenters’ Rights*” for more information.\n\n**Material U.S. Federal Income Tax Consequences of the Merger (page 130)**\n\nThe Merger is intended to qualify for U.S. federal income tax purposes as a “reorganization” within the meaning of\nSection 368(a) of the Code. Accordingly, U.S. Holders (defined in the section entitled “*Description of the Merger—Material U.S. Federal Income Tax Consequences of the Merger*”) generally will not recognize any gain or\nloss on the exchange of shares of Northfield common stock solely for shares of Columbia Financial, Inc. common stock. However, a U.S. Holder generally will be subject to U.S. federal income tax on cash received as cash consideration in the Merger or\nin lieu of any fractional share of Columbia Financial, Inc. common stock that a holder would otherwise be entitled to receive.\n\n**This\ntax treatment may not apply to all U.S. Holders. Determining the actual tax consequences of the Merger to U.S. Holders can be complicated and will depend on your particular circumstances. U.S. Holders should consult their own tax advisor for a full\nunderstanding of the Merger’s tax consequences that are particular to each stockholder.**\n\nTo review the material U.S. federal\nincome tax consequences of the Merger to U.S. Holders in greater detail, please see the section entitled “*Description of the Merger—Material U.S. Federal Income Tax Consequences of the Merger*.”\n\n**Risk Factors**\n\nYou\nshould consider all the information contained in or incorporated by reference into this document in deciding how to vote for the proposals presented in the document. In particular, you should consider the factors described under “*Risk\nFactors*.”\n\n34\n\n##### Table of Contents\n\n**RISK FACTORS**\n\n*In deciding how to vote, you should consider carefully all of the information included in this document and its Annexes, as well as the following risk\nfactors. In this section of the Joint Proxy Statement/Prospectus, the terms “we,” “us” and “our” refer to Columbia Financial and its consolidated subsidiaries or its successor Columbia Financial, Inc., Columbia\nBank MHC and Columbia Bank unless the context requires otherwise.*\n\n**Risk Factor Summary**\n\n**Merger Risks:**\n\n•\n\nIf the Conversion is not consummated, the Merger will not take place.\n\n•\n\nIf the Merger with Northfield Bancorp does not occur, the Conversion and offering would be delayed or\nterminated.\n\n•\n\nThe dilution caused by the issuance of shares of Columbia Financial, Inc.’s common stock in connection\nwith the Merger may adversely affect the market price of Columbia Financial, Inc.’s common stock.\n\n•\n\nCombining Columbia Financial, Inc. and Northfield Bancorp may be more difficult, costly or time consuming than\nexpected, and Columbia Financial, Inc. may not realize the anticipated benefits of the acquisition.\n\n•\n\nColumbia Financial has incurred, and Columbia Financial, Inc. following the closing of the Merger, will incur\nsignificant transaction and transaction-related costs in connection with the transactions contemplated by the Merger Agreement.\n\n•\n\nThe Merger Agreement may be terminated in accordance with its terms and the Merger may not be completed, which\ncould cause the results of Columbia Financial to be adversely affected, the stock prices of Columbia Financial to decline or have a material and adverse effect on the stock price of Columbia Financial and its results of operations.\n\n•\n\nThe market price for Columbia Financial, Inc. common stock following the closing of the Merger may be affected\nby factors different from those that historically have affected or currently affect Columbia Financial common stock.\n\n•\n\nThe future results of Columbia Financial, Inc. following the closing of the Merger may suffer if Columbia\nFinancial, Inc. does not effectively manage its expanded operations.\n\n•\n\nColumbia Financial will be subject to business uncertainties and contractual restrictions while the Merger is\npending.\n\n•\n\nHolders of Columbia Financial common stock will have a reduced ownership and voting interest in the surviving\ncorporation after the Merger and will exercise less influence over management.\n\n•\n\nThe m"}