Many companies will make big contributions to their pension plans again this year, raising such issues as what asset allocation companies should use and how to time their contributions. Given the trend toward increasing pension plans' allocations to fixed-income securities, consultants point out that the demand from pensions could affect the pricing of investment-grade corporate bonds.

As interest rates inched up and stock markets rallied this year, the funded status of defined-benefit pension plans has improved. Benefits consultancy Mercer put the aggregate funded ratio of S&P 1500 companies at 82% as of March 31, up from 75% at the end of 2011.

Still, S&P 1500 companies plan to contribute about $54 billion to their pension plans in 2012, based on the data in their 10-K filings, Mercer says. In 2011, those companies put about $70 billion into their plans, more than the $50 billion in contributions they said they would make in their 10-K filings.