According to Towers Watson, 2014 was a bad year for private U.S. pensions.

The company’s annual analysis of the top 100 corporate defined benefit (DB) plans found that the Towers Watson Pension 100 (TW Pension 100) had lost 8% of their average funded status at the close of last year—a fall from 90.2% at year-end 2013 to 80.2%.

Aggregate funded status numbers for DB plans overall are similar—89% to 81% for that same period—despite the fact that the value of plan assets rose, the study found. Many of the gains the plans had made in 2013 were lost, and the funding shortfall, which had shrunk that year to $128 billion, from $297 billion in 2012, ballooned back to $248 billion.

The authors of the analysis, who sifted through end-of-year 10-K filings of pension disclosures made available by the Securities and Exchange Commission (SEC), blamed falling interest rates and “significantly increased liabilities” due to longevity recalculations for last year’s losses.

Over 2014, funded status improved for just seven of the plans in the TW Pension 100, and fell, on average, between 5% and 9% for the rest.

Not all news was bad. The study cited net gains since year-end 2008 of 4% in assets over liabilities (44% vs. 40%) and, last year, higher-than-expected investment returns—almost 10%—which may have triggered correspondingly larger contributions from plan sponsors.

Comparisons with pre-Great Recession numbers, though, still show much ground to regain. More than 50% of the study group’s pensions were fully funded in 2008 versus more than 6% in 2014.

“Plan obligations rose in 2014 mainly because of lower interest rates,” the authors say. “From 2008 through 2012, discount rates fell every year, before finally rising in 2013. Then in 2014, the average discount rate fell by 83 basis points [bps]—from 4.85% to 4.02%, thereby increasing pension liabilities by 10%. At year-end 2014, the average discount rate was 236 basis points lower than it was in 2008.”

Additionally, the Society of Actuaries’ new mortality tables, introduced last fall, “played a significant role in driving up pension liabilities,” the authors say, noting that “the vast majority of plan sponsors” in their study group accordingly adjusted their mortality assumptions at the end of the year. The result: a 4.3%—or $55 billion—increase in the study group’s aggregate pension benefit obligation (PBO) in one year.

The general poor outlook since 2009 has prompted many plan sponsors to reduce risk in the ways they can, for one by reallocating assets. The study points to a trend toward fixed-income, debt and alternative investments and away from public equities. “While many factors other than investment returns affect funded status, it is interesting that six of the seven companies whose funded status improved in 2014 had fixed-income allocations of 50% or more going into 2015,” the authors wrote. “While these plans might have missed out on the strong equity gains in 2013, their fixed-income allocations were able to offset the effects of falling discount rates in 2014.”

Likewise, nearly one-quarter of the plan sponsors studied made lump-sum offers or executed bulk annuity purchases last year to de-risk their plans, the study found. Plan sponsors also lowered their costs by reducing contributions—the largest decline in six years.

“Lower funding levels are a concern for plan sponsors,” the authors concluded. “Weaker funding positions will likely necessitate larger cash contributions in the near future, and higher pension costs will most likely drive up the charge against profits for 2015, unless equity returns are strong and/or interest rates rise.”

The complete analysis can be found here.