For the past three years, Buffett's traditional bargain-hunting investment strategy has been partly stymied as debt-fueled private-equity funds and hedge funds drove asset prices out of his value-investing orbit. The result: Today he's sitting on a war chest of nearly $50 billion in cash. Now, with the shakeout in the subprime-mortgage market forcing the end of easy money and the distressed sale of assets — such as Thornburg Mortgage Inc.'s sale Monday of $20.5 billion of its top-rated mortgage-backed securities — many see Buffett, the 76-year-old chairman of the giant Berkshire Hathaway Inc. holding company, as one of the last buyers standing. There doesn't appear to be a shortage of people who are courting him these days. "I'm definitely more popular than I was a few months ago," he says — and then quips: "But I started from a low base." So what is Berkshire buying or looking to buy? Buffett hews to Berkshire's policy of not discussing potential transactions.