U.S. corporate pension deficits decreased $58 billion in August to $631 billion, according to new figures from Mercer. The deficit corresponds to an aggregate funded ratio of 72 percent as of Aug. 31, compared to a record low funded ratio of 70 percent as of July 31.

Even with the small rebound, the deficit in pension plans for S&P 1500 companies was still above 2011 levels, according to the Mercer report. U.S. equity markets rising over 2 percent during August and discount rates rising between 12 and 14 basis points helped spur the rebound. Rates had been at a record low at the end of July.

“Finally there is a bit of positive news after several months of setbacks,” said Jonathan Barry, a partner in Mercer’s Retirement Risk and Finance consulting group. “However, the overall deficit is still troubling. If these deficits persist through year end, plan sponsors will be looking at higher year-end balance sheet deficits, cash contributions and P&L expense for 2013.”