Greg Sabin for CNN reports that Joseph Kennedy Sr., the patriarch of the Kennedy family, built his fortune during the 1920s and managed to get out of the stock market before the 1929 crash. Other families that prospered during the Great Depression were headed by Michael J. Cullen and J. Paul Getty.
Sabin explains that instead of the stock market, Kennedy invested his money in real estate, liquor and movie studios, which generated profits and placed the Kennedy family into the highest financial level of American society. The PBS website for the documentary series "American Experience" notes that not only did Kennedy hold on to his wealth, but his family became even wealthier during the 1930s. The family's real estate holdings included family compounds at Hyannis Port on Cape Cod and in Palm Beach, Fla., and homes outside New York City. Kennedy even held majority ownership in the Hialeah Race Track in Miami.
Sabin reports that Michael J. Cullen was the creator of the modern supermarket and made his fortune during the 1930s with his ideas for more suburban, larger, self-serve food markets with room for automobile parking and allowances for the creation of home refrigeration. After receiving an inheritance of half a million dollars in 1930, J. Paul Getty amassed a fortune with oil stocks, with which he created an oil conglomerate.