I HAD LOADED MY LAST BUCKET OF ROCK IN THE LOADER & BACKED UP IN FIRST GEAR TO LINE UP WITH MY TRAILER. WITH THE BUCKET HALF RAISED I SHIFTED THE LOADER FORWARD WHILE STOPPED. LOADING WAS TAKI NG PLACE ON A SLIGHT HILL. AS I BEGAN TO PROCEED FORWARD I BEGAN TO RAISE THE BUCKET TO EXTEND IT OVER THE SIDE OF THE TRAILER. THE LOADER TIPPED ON THE PASSENGER SIDE WHERE IT CAME TO REST.