Retirement plans have lost nearly a quarter of their value in this economic crisis, according to a new study.  

Total U.S. retirement market assets, which include both defined contribution and defined benefit plans, tumbled 24% to $7.86 trillion in 2008, down from $10.3 trillion the prior year, according to a new report, "Retirement Market Insights 2009," released this week by Spectrem Group.  

Assets held in defined contribution plans, which include 401(k)s, fell 21% in 2008 to $3.8 trillion, down from $4.8 trillion the year before.  However, the popularity of these plans continued to increase overall, with defined contribution plans as a percentage of all retirement assets expanding to a record 49% in 2008.  

"The retirement market took a significant hit in 2008, losing nearly a quarter of its value and undermining the retirement plans of millions of Americans.  Defined contribution plans, which account for nearly half of all retirement assets and include 401(k)s, recorded a 21% overall decline," said George H. Walper, Jr., president of Spectrem Group.  

In the corporate sector specifically, 401(k) plans, which account for 71% of all corporate retirement assets, fell to $1.94 trillion in 2008. That represents a 23% decline from $2.52 trillion in 2007.  However, average annual growth remained positive at 7.8% from 1995 to 2008.

The Spectrem report is based on data derived from both public and private sources as well as Spectrem surveys.  The market sizing estimates make use of these data sources as well as Spectrem's proprietary algorithms.