Buffett, the CEO of Berkshire Hathaway , is due to appear this morning before the Financial Crisis Inquiry Commission. The congressionally-appointed panel is holding a hearing on the role of credit ratings in the financial meltdown. The hearing will be “a case study” on the actions of one firm, Moody’s , chairman Phil Angelides said.

That sort of explains why eight witnesses linked to Moody’s will appear, while no one from the other agency, S&P, was invited to attend.

Beyond that, the hearing is noteworthy primarily because it will put an unwilling witness,  Buffett, before the commission Wednesday morning in the second of three sessions.

Buffett has held a major Moody’s stake for a decade and is the rating agency’s biggest shareholder in spite of a recent series of sales. But as Fortune’s Carol Loomis noted last week, Buffett wasn’t exactly champing at the bit to share his view of how the missteps of the rating agencies helped fuel the housing bubble and subsequent bust.

He resisted testifying until the FCIC issued a subpoena to compel him to appear. And alone among the eight witnesses appearing today, Buffett hasn’t submitted written testimony.

But don’t fret, the Buffett blackout will end soon. He is scheduled to arrive at the New School in Manhattan’s Greenwich Village later this morning for a round of TV appearances prior to his testimony. And he and co-panelist Raymond McDaniel, Moody’s CEO, are due to take questions from the commissioners starting at 11:30 a.m.