General Motors Co.'s deal to cut pension obligations by $26 billion and shift plans to Prudential Financial Inc. is poised to fuel more transfers as U.S. firms face a retirement-funding shortfall the size of Greece's debt.

MetLife Inc. and Prudential are among insurers that expect the GM deal to encourage more corporations to offload plans. Pension liabilities exceed assets by more than $435 billion, according to a Bloomberg review of data disclosed by firms in the Russell 1000 Index of large U.S. companies. Greece, facing demands for austerity measures in exchange for rescue funds, had total debt of about $450 billion at the end of 2011.

Employers who endured two stock-market crashes in a decade and 10-year Treasury yields near a record low may be tempted to follow GM's lead by paying insurers to take the risk that market returns are inadequate or that beneficiaries live longer than expected. Transferring the obligations can reduce swings in earnings tied to securities and relieve companies of the need to manage large pools of money.