It's an example of perverse incentives at work. Investors and analysts want to see companies precisely hitting profit growth targets quarter after quarter. Now, pension fund expenditures lower the apparent quarterly profits, so CFOs have an incentive to favor high-risk, high-return investments (like stocks) over less risky investments. This works great in a bull market, but not so great when the market heads south.

This kind of shennanigan is pretty much an inevitable consequence of having the incentives the guy managing the money faces differing from the incentives of the guy who owns the money. That's why I like 401(k) plans a lot better than traditional pension plans: the retiree directly controls his own money.