Over the last 30 years, 401(k) and other defined contribution retirement plans have displaced defined benefit pension plans in the private sector (US). Defined benefit plans traditionally provided benefits in the form of a lifetime annuity. In contrast, in 401(k) plans, annuitization is voluntary, rare, and often not even a plan option. Participants face the challenge of decumulating their wealth over their remaining lifetimes, trading off the risk of outliving that wealth against the cost of unnecessarily restricting their consumption.