In today's low-return environment, retirees have become increasingly stressed about the potential risk of outliving their retirement assets, which in turn has led to an increasing call for strategies that at least partially annuitize a portion of the portfolio. After all, a single premium immediate annuity (SPIA) provides a lifetime stream of income that by definition cannot be outlived, and the potential for long-lived retirees to earn mortality credits creates the potential to earn significantly more cumulative return than what bonds alone can pay. In fact, a great deal of research over the past decade has shown that partial annuitization of a portfolio can improve retirement income sustainability over portfolio-based strategies alone.
Yet in new research produced by yours truly, along with retirement researcher Wade Pfau, it appears that the prior research may not be entirely correct. While it's true that for extreme longevity scenarios, SPIAs provide an unparalleled return and enhance retirement outcomes, the strategy as commonly implemented is also an indirect form of a bucket strategy that disproportionately liquidates fixed-income assets in the early years and lets the rest of the (risky) portfolio run. By reducing withdrawals from risky assets in the early years, the exposure to potentially unfavorable return sequences is diminished, even as the total allocation to equities rises throughout retirement.
In fact, as the results show, the majority of the benefits commonly attributed to partial annuitization are actually just the indirect result of a bucket strategy that produces a rising equity glidepath. While SPIAs do still provide superior results for very long-lived retirees, it truly takes extreme longevity - i.e., married couples living beyond age 100 - before the contribution from mortality credits actually outweighs the benefits of just using a strategy that liquidates more fixed income in the early years and allows equity exposure to rise. Accordingly, the bottom line is that for retirees who truly want to hedge extreme longevity, the benefits of SPIAs remain unmatched, but for most retirees who will not live that long the reality is that SPIAs not only fail to provide benefits, but they can actually produce results inferior to just replicating the rising equity glidepath without annuitizing at all!