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Born Pierre Sylvain Désiré Gérard David-Weill in Paris, France, he was the son of Flora Raphael and David David-Weill (1871-1952), Chairman of Lazard Frères. He followed in his father's footsteps and in 1927 became a partner in the Paris office of the family's bank at the time under the direction of the Raymond Philippe.
In 1932 Pierre David-Weill married Berthe Haardt with whom he had a son, Michel David-Weill (born 1932) and a daughter, Eliane David-Weill born in 1935.
Along with Lazard Frères minority partner, André Meyer, Pierre David-Weill and his family fled the German occupation of France during World War II to the safety of the United States. There, he took charge of the firm's office in New York City where he remained until the liberation of France by Allied Forces in 1944. On his return to Paris, he left André Meyer in charge of American operations and along with Felix Rohatyn, they expanded Lazard Frères business to make it a leading Euro-American investment bank.
Pierre David-Weill died in 1975. Despite converting to Catholicism in the mid-1960s, he is interred with his wife in the Jewish section of the Cimetière du Montparnasse in the Montparnasse Quarter of Paris.