David Gottesman, a protégé of Warren Buffett who built a powerful Wall Street investment house, First Manhattan, which manages more than $20 billion for its clients, and who presided over it for a half-century, died on Sept. 28 at his home in Rye, NY. He was 96.

Mr. Gottesman began First Manhattan in 1964 with the profits from a venture in which he bought Computer Systems Inc., a bankrupt maker of computers used on missile ranges. Unrealistic projections led to a three-year blood bath of red ink, but the company succeeded in designing a computer to regulate the output of oil refineries. Schlumberger Ltd., a major oil field company, sought to buy Computer Systems, but Mr. Gottesman and his investors retained 20 percent. The company soared in value when shares were later offered to the public.

But it was his investment in Mr. Buffett’s company, Berkshire Hathaway, of which he was a board member, that constituted the bulk of Mr. Gottesman’s fortune. “There probably has never been a better return on any stock held for 44 years in the history of Wall Street,” Mr. Gottesman wrote a decade ago, calculating at the time that his shares had grown to 6,000 times their initial value.

Mr. Gottesman’s charitable donations included a bicycle path circling Jerusalem, and the Gottesman Hall of the Planet Earth at the American Museum of Natural History.