Potential PBGC problem: $13.5 billion GM liability

"The PBGC estimates its exposure to contingent liabilities of the Big Three U.S. automakers — GM; Ford Motor Co., Dearborn, Mich.; and Chrysler LLC, Auburn Hills, Mich. — totaled $41 billion as of Jan. 31. Only $13 billion of that represents net claim exposure, the PBGC estimates. The PBGC didn't have a separate breakout for each company. The net claim exposure represents what the PBGC estimated it would have to cover."