John Langeloth Loeb Sr., a leading member of the investment community who was long the head of the Wall Street firm of Loeb, Rhoades & Company, a predecessor of Shearson Lehman/American Express, died yesterday at his Upper East Side home in Manhattan. He was 94 and also had homes in Purchase, N.Y., and Lyford Cay, Nassau, the Bahamas. John Loeb Sr., a philanthropist who was active in political affairs as well as a pillar of Wall Street's Old Guard, was a founder with his father and two others of Carl M. Loeb & Company in 1931. That firm merged with Rhoades & Company in 1937 to form what became Loeb, Rhoades. In 1984, after a succession of mergers in the intervening years, he was named an honorary chairman of the successor firm, Shearson Lehman/American Express, a subsidiary of the American Express Company. Over the years, Loeb, Rhoades had remained to a considerable extent a family affair, with John Loeb's partners including his brother, Henry; his son, John Loeb Jr., and two nephews. He was born on Nov. 11, 1902, in St. Louis, the son of Carl Morris Loeb, an immigrant from Germany. Carl Loeb made a fortune early in life by gaining control of the American Metal Company and went on to become a co-founder with his son and two other partners of Loeb, Rhoades. John Loeb's mother was the former Adeline Moses, an Alabama banker's daughter who traced her American lineage to pre-Revolutionary times. After briefly attending Dartmouth College, Mr. Loeb transferred to Harvard College and graduating from there in 1924. Mr. Loeb and his wife, the former Frances Lehman, entertained senators, mayors, governors and other political figures in their 14-room East Side home. He married Miss Lehman, the daughter of Arthur Lehman of the Lehman Brothers banking firm, in 1926. She was the granddaughter of Adolph Lewisohn, the banker and philanthropist, and niece of Herbert H. Lehman, who later became Governor of New York and a Senator. In addition to his son, John Jr., of Purchase, Mr. Loeb is survived by another son, Arthur Lehman Loeb of Manhattan; three daughters, Ann Loeb Bronfman of Washington, who is Arthur's twin, Judith Loeb Chiara of Purchase and Deborah Loeb Brice of London; 14 grandchildren, including Edgar Bronfman Jr., the president of Seagram; a brother, Henry A., of Manhattan; and a sister, Margaret Loeb Kempner of Purchase, and numerous great-grandchildren.