In retirement plans, one of the more intransigent concerns for policy makers, providers, and plan sponsors alike is what has been called the "annuity puzzle" — the reluctance of American workers to embrace annuities as a distribution option for their retirement savings.

What economists call "rational choice theory" suggests that at the onset of retirement individuals will be drawn to annuities, because they provide a steady stream of income, and address the risk of outliving their income. And yet, given a choice, the vast majority doesn't.

Over the years, a number of explanations have been put forth to try and explain this reluctance: the fear of losing control of finances; a desire to leave something to heirs; discomfort with entrusting so much to a single insurer; concern about fees; the difficulty of understanding a complex financial product; or simple risk aversion — all have been studied, acknowledged, and, in many cases, addressed, both in education and in product design, with little impact on take-up rates.