NISA Investment Advisors' Pension Surplus Risk index fell to 9.3% in April, down 10 basis points from the previous month.
It was the third straight month the index was down. NISA said the decrease was due to a decline in return-seeking asset volatility and the annual reconstitution of the PSRX's constituents.
The average funded status of plans in NISA's universe was 88.8% in April, compared to 89.3% at the end of March.
The Pension Surplus Risk index aims to be a forward-looking estimate of the funded status volatility of U.S. defined benefit pension funds, based on averages of the 100 largest corporate plans.