Read more: http://www.businessinsider.com/henry-blodget-moodys-gets-wells-notice-sec-may-order-ratings-agency-to-cease-and-desist-2010-5
Voltron says: The investigation is with respect to some 2008 constant-proportion debt obligations (CPDOs) that Moody's knew were overrated due to a "computer bug" but knowingly did not correct the error. The US may revoke Moody's charter to rate securities (NRSRO). Coincidently Moody's is now saying the the US may lose it's triple-A credit rating as soon as 2013. Unlike bond issuers, the US does not pay Moody's for ratings.