Pursuant to a congressional request, GAO reviewed the Pension Benefit Guaranty Corporation's (PBGC) pension plans and its vulnerability to unfunded liabilities, focusing on: (1) factors which cause hidden liabilities; (2) the impact on recent claims against the pension insurance program; and (3) PBGC ability to control these factors.

GAO found that: (1) PBGC exposure to private pension unfunded liability claims totalled $2.7 billion, which included $990 million in hidden liabilities; (2) when pension plans terminated with insufficient assets, PBGC frequently absorbed unfunded liabilities which were considerably greater than the plan reported; (3) 81 percent of the hidden liabilities increased because of pension plan liabilities and decreases in pension plan assets; (4) differing actuarial assumptions including interest rates, mortality rates, and retirement age accounted for 31 percent of discrepancies between the reported plan liabilities and PBGC calculations; (5) reasons for reductions in pension plan assets included lump sum payments, annuity purchases, unpaid contributions, market losses, inappropriate asset use, and asset overvaluation; (6) 25 percent of PBGC liability resulted from company pension plan shutdown benefits; (7) PBGC has few tools to control its exposure to unfunded liabilities, since PBGC guarantees worker pensions without regard to the amount of unfunded liability; (8) PBGC inability to restrict claims has created an institutional moral hazard for plan sponsors by giving them incentives to shift their liabilities onto PBGC; and (9) tools which could assist in controlling hidden liabilities could impose additional costs on plan participants, plan sponsors, and the government.