Most of the pension shortfall using the current methodology is attributable to the plunge in the stock market in the years 2007-2009. If pension funds had earned returns just equal to the interest rate on 30-year Treasury bonds in the three years since 2007, their assets would be more than $850 billion greater than they are today. This is by far the major cause of pension funding shortfalls. While there are certainly cases of pensions that had been under- funded even before the market plunge, prior years of under-funding is not the main reason that pensions face difficulties now. Another $80 billion of the shortfall is the result of the fact that states have cutback their contributions as a result of the downturn.
Unforced variations: July 2016
31 minutes ago