Robert L. Clark (North Carolina State University, Department of Economics) & John Sabelhaus (University of Maryland, Department of Economics) have published How Will the Stock Market Crash Affect the Choice of Pension Plans?, 62 Nat'l Tax J. 477 (2009).  Here is the abstract:

For the past three decades, there has been a significant movement away from defined benefit pension plans in the private sector toward greater use of defined contribution plans, especially 401(k) plans. In contrast, retirement plans in the public sector remain primarily defined benefit plans. The stock market crash of 2008 had a dramatic effect on pension balances across all types of plans; private defined benefit, private defined contribution, and state and local plan assets all fell by more than 25% in 2008. This paper examines the trends in plan type up to 2008, the impact of the crash on pension holdings, and the likely responses by employers and employees to the current economic climate.