Matt Levine’s Money Stuff: UK Pensions Got LDI Margin Calls

LDI

Here is a simple model of a pension fund. You know you will need to pay out a bunch of money 30 years from now, so you buy some 30-year government bonds and hold them to maturity. When the bonds mature in 30 years, you have money, which you give to the pensioners, and you’re done. This model is obviously oversimplified, but it’s a good start.

Let me make three points about this model. First, a financial point: Doing a pension fund this way is expensive. Thirty-year UK gilts (government bonds) paid about 2.5% interest this summer. If you want ...