Warren E. Buffett has two cardinal rules of investing. Rule No. 1: Never lose money. Rule No. 2: Never forget Rule No. 1.

Well, a lot of old rules got trashed when the financial crisis struck — even for the Oracle of Omaha.

At 79, Mr. Buffett is coming off the worst year of his long, storied career. On paper, he personally lost an estimated $25 billion in the financial panic of 2008, enough to cost him his title as the world’s richest man. (His friend and sometime bridge partner, Bill Gates, now holds that honor, according to Forbes.)

And yet few people on or off Wall Street have capitalized on this crisis as deftly as Mr. Buffett. After counseling Washington to rescue the nation’s financial industry and publicly urging Americans to buy stocks as the markets reeled, in he swooped. Mr. Buffett positioned himself to profit from the market mayhem — as well as all those taxpayer-financed bailouts — and thus secure his legacy as one of the greatest investors of all time.

When so many others were running scared last autumn, Mr. Buffett invested billions in Goldman Sachs — and got a far better deal than Washington. He then staked billions more on General Electric. While taxpayers never bailed out Mr. Buffett, they did bail out some of his stock picks. Goldman, American Express, Bank of America, Wells Fargo, U.S. Bancorp — all of them got public bailouts that ultimately benefited private shareholders like Mr. Buffett.

If Mr. Buffett picked well — and, so far, it looks as if he did — his payoff could be enormous. But now, only a year after the crisis struck, he seems to be worrying that the broader stock market might falter