AIG's risk-modeling system had proven "very reliable," Sullivan said, and since the transactions were so "conservatively structured," AIG had "a very high level of comfort" with its risk models. Federal investigators are probing whether Sullivan and other AIG executives misled investors at this meeting, according to the Wall Street Journal. February 11, 2008 : AIG discloses in a regulatory filing that its auditor, PricewaterhouseCoopers, has found a problem: a "material weakness" in its valuation of the swaps. AIG therefore needed to "clarify and expand" its prior disclosures.