Berkshire Hathaway Inc. confirmed on Friday that Warren Buffett will testify under subpoena before a U.S. panel examining the causes of the 2008 financial crisis.

Buffett, 79, rebuffed earlier requests by the Financial Crisis Inquiry Commission to submit to voluntary questioning, resulting in Tuesday's subpoena, Berkshire said.

Carrie Kizer, an assistant to Buffett, confirmed the accuracy of a Fortune magazine article on Thursday that revealed the subpoena and Buffett's resistance to testifying.

Buffett, Moody's Corp. Chief Executive Raymond McDaniel, and five other current and former Moody's officials will testify on June 2, as the commission examines credit ratings and how investors use them.

The Congressionally appointed commission is examining the causes of the worst financial crisis since the 1930s and is trying to find flaws that could be remedied through reforms. It is slated to issue a report by Dec. 15.

Moody's is the parent of credit rating agency Moody's Investors Service. Berkshire had a 13 percent stake in Moody's as of March 31, regulatory filings show.

Buffett is the world's third-richest person, with most of his fortune coming from Berkshire. He has since 1965 run the Omaha, Neb.-based conglomerate, which now has roughly 80 companies and tens of billions of dollars of investments.