The Origins and Severity of the Public Pension Crisis

"In sum, most states face pension shortfalls that are manageable, especially if the stock market does not face another sudden reversal. The major reason that shortfalls exist at all was the downturn in the stock market following the collapse of the housing bubble, not inadequate contributions to pension funds."

 Source: http://www.cepr.net/index.php/publications/reports/the-origins-and-severity-of-the-public-pension-crisis