A Towers Watson news release said DB plans outperformed 401(k) plans by roughly 1 percentage point in 2008, although both types of plans lost value, and while most DB plans incurred losses for 2008, some actually reported small positive returns. By contrast, all DC plans in the study had losses of at least 10%, and a few had losses greater than 40%, more than any DB plan in the study, according to the news release.

According to the analysis, DB plans had median investment returns of -25.27% in 2008, while DC plans had median returns of -26.20%. The 2008 results are based on a survey of 79 employers that sponsor one DB plan and one 401(k) plan. Towers Watson said these results will be updated and expanded as additional data becomes available.

A broader analysis of more than 2,000 plan sponsors shows that DB plans had a median return average of 7.71%, while DC plans had a median return of 6.78% in 2007. This finding is consistent with earlier analyses, which show that DB plans have consistently outperformed DC plans by an average of about 1 percentage point per year during both bull and bear stock markets, according to Towers Watson.

“Participants in 401(k) plans were less likely than DB plan sponsors to rebalance their asset portfolios while stock values ran up, leaving them more vulnerable to market declines,” explained Mark Ruloff, senior consultant at Towers Watson, in the news release. “Many DB sponsors had been reducing their exposure to equities and already shifted toward more conservative investment strategies in 2007, which helped to mitigate their losses.”

Plan Size Comparison

The analysis also found that, between 1995 and 2007, larger retirement plans—both DB and DC—realized investment returns higher than those of smaller plans. During this period, the largest sixth of the analyzed DB plans outperformed the smallest sixth by approximately 3 percentage points, compared with a difference of approximately 0.7 percentage points between the median investment returns of the largest and smallest 401(k) plans.

"Size influences the performance of DB plans more than it affects DC plans because larger pension plans can afford to spend more on professionals to manage assets and use more sophisticated strategies," said Mark Warshawsky, senior retirement researcher at Towers Watson. "On the other hand, 401(k) plan participants often do not optimize their investment strategies. Even with more investment education and better default investment options for 401(k) plan participants, DC plans do not replicate all the advantages of DB plans and are unlikely to outperform DB plans, which generally have extended investment horizons and economies of scale."

Sylvia Pozezanac, senior consultant at Towers Watson, said the findings of the analysis are not surprising as "[m]any DB plans, especially the larger ones, have adopted strategies where assets are invested in a way that their movement would more mirror those of pension liabilities and have diversified into alternative investments"—resulting in a larger proportion of fixed income instruments and other assets as opposed to equities, which fared better than stocks in the recent market downturn.
Effect of Fees on Rates of Return

A report on the Towers Watson analysis included a discussion on the effect of plan expenses on rates of return. The previous analysis focused on returns based strictly on income performance.

The report noted that DB plans typically report income net of investment expenses. However, expenses for 401(k) plans, including administrative costs, are typically deducted from investment returns. As a result, Towers Watson said, Form 5500 data does not reflect differences in returns for DB and DC plans arising from embedded non-investment costs in the investment income component—especially for mutual fund investments.

In 2008, 38% of plan assets in 401(k) plans were invested in mutual funds, compared with only 12% in DB plans. Mutual funds for 401(k) plans had an average weighted expense of 66 basis points in 2008. With 38% of 401(k) plan assets invested in mutual funds, a reasonable assumption is that these fees reduce rates of return by 25 basis points.

According to Towers Watson's 401(k) fee data, roughly one-third of mutual fund fees are actually bundled administrative costs, so 401(k) returns lose an average of 8 basis points due to bundled administrative costs incorporated in investment fees. Between 1995 and 2007, asset-weighted median returns were 1.07% higher in DB plans than in 401(k) plans, and adding 8 basis points to 401(k) plan returns for implicit bundled administrative costs results in a net difference of almost exactly 1 percentage point.