NISA Investment Advisors' Pension Surplus Risk index sank to 5.3% in April, falling below March's 6.1% and to its lowest reading since its inception in December 2006. The month also saw the average plan funding ratio rise 3.3 percentage points to 92%, the largest single month increase since February 2015.
The volatility of the index's asset component fell to 7.2% from 7.7%, while the volatility of the liability component was unchanged at 6.1%. During the month, global equities, as measured by the MSCI ACWI index, rose 3.2%, while the S&P 500 index was up 3.9%. High-grade corporate yields rose slightly to 3.41% from 3.39%.
The Pension Surplus Risk index represents an expected rise or fall in assets given a one-standard deviation change in returns in a given year.