Well, this was inevitable. CalPERS, the pension fund for state employees and the largest pension plan in the country, took a big hit in the stock market, losing 31 percent of its value, or $81.4 billion, in the last twelve months. This isn't quite as big a problem as it sounds like, as the pension fund is designed to finance retirement payments over the long term, and the plan can survive short-term drops in the stock market. (Assuming this is a short-term drop, of course.) Nonetheless, as the San Francisco Chronicle reports, CalPERS is a defined benefits plan, which means the retirement payments can't reduced, no matter how much money is in the system. So pension officials may have to ask state and local governments to put more money in the system if its fortunes don't turn around.