Warren E. Buffett's annual meeting is usually a chance for the billionaire to show how the mistakes of others enrich Berkshire Hathaway Inc.'s shareholders. This weekend's gathering might focus on whether Berkshire made missteps.

The annual meeting in Omaha, Neb., will be the first opportunity for many investors to ask the 74-year-old Buffett about regulatory investigations into transactions between a Berkshire unit and American International Group Inc., the world's largest insurer.

Berkshire's reinsurance operations have profited for years from clients who were willing to pay for a type of coverage some credit-rating companies deemed foolish, though usually legitimate.

The reinsurance policies, which often offer an immediate accounting benefit at the expense of long-term earnings, have embroiled Berkshire in state and federal investigations of at least three companies that might have used them improperly.

"There are many areas of irrational behavior that have rewarded Berkshire over the years," said Thomas Russo, a partner at Gardner Russo & Gardner in Lancaster, Pa., which has about 15 percent of its $2 billion investment pool in Berkshire stock.

"The question for Buffett is: In providing these [reinsurance] policies, is he participating in that conduct? Are they somehow culpable? I don't think so."

Berkshire and Buffett haven't been accused of wrongdoing in the AIG transaction, and New York Attorney General Eliot Spitzer, whose investigators interviewed Buffett on April 11, said then that Buffett was a "cooperative witness" and not a target.

Insurance regulators in Virginia and Tennessee have sued Berkshire's General Re Corp. for contracts with a failed medical malpractice insurer. And the liquidator of a collapsed Australian insurer said it might assert claims against General Re.

Buffett, who has run Berkshire for four decades, and General Re Chief Executive Officer Joseph P. Brandon didn't respond to voicemail messages.

General Re said last month that it was cooperating with probes in Australia and denied the allegations in the Virginia and Tennessee suits.

Buffett, the world's second-richest man in Forbes magazine's ranking after Microsoft Corp. founder Bill Gates, has often benefited from others' mistakes, buying billions of dollars of assets on the cheap from investors who failed to see their value.

The billionaire's investing skill and defense of shareholders' rights has won him legions of followers. A $10,000 investment in Berkshire the day Buffett took control in 1965 would be valued at about $46 million today.

Buffett has picked up dozens of companies in industries as diverse as paint, candy and corporate-jet timeshares. Insurance is Berkshire's biggest business, accounting for 59 percent of the $7.44 billion it earned in pretax operating profit last year.

The insurance industry probes have shined a spotlight on a type of reinsurance known as finite. The contracts typically allow the buyer, another insurer, to increase its reported net worth, while giving up future income from investments.

Abuses arise when too little risk is transferred to the reinsurer to justify the favorable accounting that allows the buyer to increase its net worth.

The suits by Virginia and Tennessee argue that General Re had a secret side agreement with the failed medical malpractice insurer, Reciprocal of America, that limited General Re's risk and allowed Reciprocal to hide its financial weakness.

Berkshire said last month that such a side letter existed with HIH Insurance Ltd., which became Australia's biggest corporate failure when it collapsed in 2001. The company said it was written before Berkshire's 1998 purchase of General Re.

The contracts with AIG overstated the AIG's premiums and reserves for claims by $500 million. Buffett said in a March 29 statement that he wasn't aware of the details of the AIG deal or any improper use.

Buffett and Berkshire haven't faced this level of scrutiny since the near-collapse of Salomon Brothers in a 1991 Treasury bond trading scandal, Russo said.

Buffett, who had invested $700 million of Berkshire's money in the firm, took charge of Salomon and put his own reputation on the line to appease regulators and the Treasury, according to Roger Lowenstein's biography, Buffett: The Making of an American Capitalist.

"Warren Buffett is above reproach," said Robert A. "Bobby" Kotick, who has attended five Berkshire meetings and is chief executive officer of Activision Inc., the third-largest U.S. video game maker. He has owned Berkshire shares personally since 1984.

Kotick and Donald A. Yacktman, president of Yacktman Asset Management in Buffalo Grove, Ill., are among Berkshire shareholders who say Buffett's track record suggests he will emerge unscathed from the reinsurance probes.

"As a human being, he puts his pants on one leg at a time, and so he could have made a mistake along the way," Yacktman said. "Is it probable? No."