SAN FRANCISCO (MarketWatch) — He gave long-term investor a whole new meaning.

Contrarian investor Irving Kahn, known for making money in the 1929 Crash by shorting stocks, has died at the ripe age of 109. But he left his mark on Wall Street.

Up to the end, Kahn served as chairman of Kahn Brothers Group Inc., which was founded in 1978 and has about $1 billion under management. Kahn reportedly still went to his midtown Manhattan office three times a week, taking a short taxi ride from his Upper East Side apartment.

Kahn’s death was reported through a brief paid obituary in the New York Times on Thursday. No specific cause of death was listed.

According to the firm’s website, Kahn Brothers invests primarily in undervalued and unpopular securities.

In its most recent filing with the Securities and Exchange Commission, Kahn Brothers showed large stakes in such companies as BlackBerry Ltd. US:BBRY , Citigroup Inc. C, -1.47% , BP PLC BP, -3.47% , New York Times Co. NYT, -0.99% , Pfizer Inc. PFE, -0.51% , and Merck & Co. MRK, +0.19%

Other than the experience of the stock market crash, Kahn’s focus on value investing was reinforced by being a teaching assistant to Columbia University lecturer Benjamin Graham, who counted Warren Buffett as a pupil.

In an interview with U.K.’s Telegraph in August, Kahn reflected on how he made money during the Crash of 1929 by shorting stocks.

His longevity was as heralded as his stock-picking prowess.

About six years ago, Kahn was recruited to participate in the Longevity Genes Project at Yeshiva University’s Albert Einstein School of Medicine. The study tracked the genetics of people who have lived to near 100 years or over and were still in relatively good health.

A profile of Kahn in that study appears below: