Born on August 10, 1900, in Anamosa, Iowa, Josephine Perfect grew up in Brooklyn, New York. After graduating from Brooklyn Heights Seminary and attending Colorado College for a year, 1918╨1919, she became active in various civic groups in Brooklyn, notably the Junior League. With her sister she also operated a successful Christmas card business. In August 1942 she married Charles U. Bay, a senior partner in the brokerage firm of A. M. Kidder & Co. She took an active interest in his business from the start. During 1946╨1953 she accompanied her husband to Norway, where he served as U.S. ambassador and she worked in various ways to help relieve the distresses left by World War II. In 1955, when Charles Bay fell ill, Josephine Bay was elected to a limited partnership in A. M. Kidder, and she also succeeded him as a director of the American Export Lines. (Charles Bay died in December 1955.) In 1956 she was chosen chairman of the executive committee of American Export (a passenger and shipping firm then doing $60 million gross annual business), and in December of that year she was elected to the presidency and chairmanship of the board of A. M. Kidder.
Bay was the first woman to head a member firm of the New York Stock Exchange. In February 1959 she moved up to chairman of the board of American Export Lines, a post she held until the next year. She remained at the head of A. M. Kidder until her death in New York City on August 6, 1962. She was succeeded by her second husband, C. Michael Paul, whom she had married in January 1959, and he retained the post until A. M. Kidder went out of business in June 1963.
