A rising US discount rate pushed liabilities down for the country’s largest corporate pensions, despite a year of poor returns, Russell Investments reported.

Deficits for the $20 Billion Club—the 20 publicly-listed US corporations with the largest pension liabilities, including AT&T, FedEx, and Ford—fell by $12 billion to $182 billion in 2015 as a result. The 6% decline came in spite of “anemic” returns as rising interest rates decreased the value of liabilities.

Liabilities across the 20 pensions fell from $968 billion to $913 billion. This was due in part to discount rates rising from 4% to 4.4%, which in turn decreased the actuarial value of liabilities by $34.6 billion.

“Several significant effects, none of which was overwhelming, combined to create a small net improvement in funded status,” Chief Research Strategist Bob Collie said.

The deficit improvements masked a decline in total assets from $774.2 billion to $732.3 billion during the year, as the cost of paying benefits outweighed both investment returns and employer contributions. Portfolios delivered an average gain of just 1%, with returns ranging from -1.6% to 2.3%. Employer contributions dropped to $13.4 billion, the lowest level since 2008.

“The total contribution by plan sponsors in 2015 was less than the new benefits accrued in the year—so contributions did not even cover service cost, let alone make any dent in [2014’s] $194 billion deficit,” Collie wrote, noting that low contributions were likely driven by funding relief provided by clauses in two transport funding acts.

Changes in currency valuations also meant the dollar value of non-US assets and liabilities fell “fairly substantially” in 2015.

“Many of these corporations have quite substantial overseas plans, and the net effect on funded status was a notable positive,” Collie wrote.

Source: Russell Investments

Related: Liabilities Soar for the $20 Billion Club & Corporate Pensions Likely to Miss 2015 Return Expectations