Bill Bengen: Revisiting Safe Withdrawal Rates

Episode Summary

Executive Summary: Morningstar’s Christine Benz and Jeff Batek interview retirement researcher William Bengen about the evolving “4% rule,” arguing that withdrawal safety depends heavily on starting valuations and inflation. Bengen says today’s high CAPE, rising inflation, and low yields make retirement planning unusually difficult, favoring more flexible, risk-managed, and diversified approaches.

Main Topics: Origins and limits of the 4% rule (Priority: 5/5): Bengen reviews how his 1994 research produced the original safe withdrawal framework and notes that pre-1990 guidance varied widely, from very conservative to aggressive. Valuations plus inflation as withdrawal-rate predictors (Priority: 5/5): He explains that CAPE alone is only moderately predictive, but adding starting inflation creates six inflation regimes that map much more closely to historically safe withdrawal rates. Current market regime is unusually challenging (Priority: 5/5): Bengen characterizes the present mix of high valuations, rising inflation, and low bond yields as unprecedented and difficult to translate into a reliable starting withdrawal rate. Spending patterns, healthcare, and individualized planning (Priority: 4/5): The conversation explores how retirees often spend less later in life but face offsetting medical and legacy costs, making spending trajectories highly personal rather than universally assumable. Asset allocation and diversification in retirement (Priority: 5/5): Bengen argues that very high equity allocations are generally risky for retirees, favors balanced stock/bond mixes, and says broader diversification across small, mid, and international stocks can help. Rebalancing, withdrawal sourcing, and tactical risk management (Priority: 4/5): He suggests less-frequent rebalancing may improve withdrawal sustainability, and he favors active risk management and third-party input over pure buy-and-hold in today’s environment. Retirement beyond finances (Priority: 3/5): Bengen reflects on his own retirement as a productive “fourth career,” emphasizing the importance of purpose, hobbies, and continued learning.

Key Arguments: Safe withdrawal rates cannot be determined from valuation alone; starting inflation materially changes the historical outcome. Early retirement years are especially critical because both market declines and inflation permanently shape the withdrawal path. High inflation early in retirement is more dangerous than inflation that arrives later, because it compounds future withdrawal needs. Very high equity allocations can reduce, not increase, sustainable withdrawals because bear markets can devastate retirement portfolios. Diversifying beyond U.S. large caps and intermediate Treasuries has historically lifted sustainable withdrawal rates, though gains may be diminishing. Retirees should not assume spending automatically falls enough later in life to justify aggressive early withdrawals; healthcare and legacy goals can offset spending declines. In the current environment, risk management should outweigh return maximization for retirees and their advisors. Flexible spending and tactical asset management may help, but robust retirement software and practical tools are needed before these ideas are widely adopted.

Data Points: Original safe withdrawal rate: 4% to 4.15% - Bengen’s early research using U.S. large-cap stocks and intermediate-term Treasuries Later revised withdrawal rate: 4.5% - Bengen says this result came from modeling small-cap stocks as a single asset class Latest withdrawal rate estimate: 4.7% - Bengen’s newer research with four asset classes, three of them stocks Potential upper bound: around 5% - Bengen’s rough estimate for how high withdrawal rates might rise with further diversification CAPE ratio in current environment: almost 40 - Bengen says valuations are near extreme historical levels Inflation regimes: 6 regimes - He divides history into six bands of roughly 2.5 percentage points of starting inflation Low inflation regime: 0% to 2.5% - One of the inflation buckets in Bengen’s framework Moderate inflation regime: 2.5% to 5% - He describes this as “modern inflation” in the framework Historical high withdrawal rate: as high as 13% - Seen historically when low inflation coincided with cheap stock valuations Early retirement window: first 5 to 7 years - Bengen says this period largely sets the tone for retirement outcomes Late 1950s safe withdrawal rate: 6.5% - Example of low inflation and moderate valuation supporting a higher rate Current personal equity allocation: about 20% equities - Bengen says his own portfolio is heavily de-risked due to valuation concerns Retirement date referenced: 2013 - Bengen says he retired and used a 4.5% rate then Current effective withdrawal rate: around 3.5% - Because his portfolio has grown since retirement Suggested equity range: 50% to 60% - Bengen’s preferred general allocation for retirees Very high equity allocation: 90% to 100% - He says this can be reasonable only in very cheap markets, such as around 1982

Pivotal Quotes: "When you have low inflation and you have cheap stock market valuations, when you get your very high withdrawal rates, as high as 13% historically..." — William Bengen: He explains his framework combining inflation regimes with CAPE to estimate safe withdrawal rates "What happens in those first five to seven years of retirement pretty much are going to set the tone for the range of retirement." — William Bengen: He stresses the importance of the early retirement period for both inflation and market returns "Risk management, to me, is at the fore consideration today, not return." — William Bengen: He argues retirees should prioritize capital preservation over maximizing upside in the current market environment

Implications: For retirees and advisors, valuation alone is not enough; inflation timing and early-retirement sequence risk matter greatly. The episode suggests more conservative, diversified, and actively managed withdrawal strategies may be prudent until planning tools better integrate these factors.