Big U.S. employers are expected to pay $100 billion into pension plans this year – among them General Motors, Boeing and 3M.

That’s 63 percent more than two years ago, as low interest rates continue to boost companies’ liabilities.

Companies are caught because the Federal Reserve Board’s vow to keep rates at current levels until 2014 means pension plans’ fixed-income investments are stagnating, just as new rules shorten the time available to shore up funding.

Read more at Bloomberg.