If you've spent any time thinking about retirement investing, you've probably encountered the rule of thumb: subtract your age from 100 and put that percentage in stocks. A 60-year-old retiree, by this logic, should hold 40% stocks and 60% bonds. It's simple, intuitive, and deeply incomplete.

The problem isn't that this heuristic is always wrong. It's that it treats asset allocation as a one-dimensional question about growth versus safety. In retirement, the real question is more specific and more consequential: given that I'm withdrawing money every year, can my portfolio survive the worst historical drawdowns without running out? The answer depends on your allocation—but not in the way most people assume.

What the Historical Data Actually Shows

Using US market data from 1928 through 2023—covering the Great Depression, World War II, stagflation, the dot-com bust, the 2008 financial crisis, and the 2022 rate shock—we can test how different allocations performed for a retiree withdrawing 4% of their initial portfolio (adjusted for inflation) over a 30-year period. These results come from running every overlapping historical period, not cherry-picked timeframes.

Here's what the data shows, approximately:

100% stocks: The highest median ending portfolio value by a wide margin, but also the most volatile ride. Historical success rate of roughly 95%. The failures are concentrated in retirements starting in the late 1960s, when stocks delivered poor real returns for over a decade while sequence risk ravaged portfolios.
80/20 stocks/bonds: Slightly lower median ending value than 100% stocks, but a marginally higher success rate of approximately 96%. The bond allocation cushions early drawdowns just enough to let the equity portion recover. For many retirees, this is the sweet spot.
60/40 stocks/bonds: The classic “balanced” portfolio. Success rate around 93%. Noticeably less volatility, which means a smoother psychological ride, but lower long-term growth. This allocation works well for shorter retirements or retirees with other income sources.
40/60 stocks/bonds: Here's where it gets counterintuitive. The success rate actually drops—to roughly 85–88%. More bonds means less volatility, but the portfolio can't grow fast enough to sustain three decades of inflation-adjusted withdrawals.

These are approximate figures based on historical simulation. Your results will differ based on the exact data set, whether you include dividends, and how you handle rebalancing. The key insight isn't the precise numbers—it's the shape of the curve. Run your own numbers to see how your specific allocation performs.

The Bond Paradox

There's a deeply held belief that bonds are the “safe” part of a retirement portfolio. In one sense, this is true: bonds reduce year-to-year volatility, and they historically hold up better than stocks during market crashes. If your only goal is to minimize the chance of a scary quarterly statement, bonds deliver.

But retirement isn't a one-quarter problem. It's a 20- to 40-year problem. And over those time horizons, bonds introduce a different kind of risk that doesn't show up on a risk tolerance questionnaire: the risk that your portfolio slowly bleeds out because it can't generate enough real growth to offset your withdrawals plus inflation.

Consider a retiree with a 40/60 stock/bond portfolio withdrawing 4% per year. In a year where inflation runs 3% and bonds yield 4%, the real return on the bond portion is roughly 1%. Meanwhile, the retiree is pulling out 4% of the original portfolio value (inflation-adjusted). The math simply does not work over long periods unless the stock portion carries the portfolio—and at 40% allocation, it often cannot.

This is the paradox: the allocation that feels safest can actually be the most dangerous over a full retirement. The optimal stock allocation for a 30-year retirement at a 4% withdrawal rate is typically somewhere between 50% and 80%—considerably more aggressive than most retirees expect, and more aggressive than what most financial advisors recommend for clients over 60.

The Role of Cash and Gold

Stocks and bonds aren't your only options. Two other asset classes show up regularly in retirement portfolios: cash equivalents (money market funds, T-bills) and gold.

Cash

Holding one to two years of expenses in cash or short-term instruments serves a legitimate purpose: it lets you avoid selling stocks during a downturn. If the market drops 30%, you can spend from your cash reserve while equities recover, rather than locking in losses. This is a behavioral and practical buffer, not a return-generating allocation.

The problem comes when retirees hold too much cash. Historically, T-bills have barely kept pace with inflation, and after taxes they often lose purchasing power. A portfolio with 20% or more in cash faces the same slow-bleed problem as an overly conservative bond allocation, just worse. Cash is a tool for short-term liquidity, not a long-term retirement strategy.

Gold

Gold is a more complicated story. It has genuine value as an inflation hedge during specific economic scenarios—particularly stagflation, where stocks and bonds both struggle. During the 1970s, gold delivered spectacular real returns while a traditional 60/40 portfolio got crushed by inflation. A small gold allocation (5–15%) can improve outcomes in those worst-case scenarios.

But gold also has extended periods of terrible real returns. From 1980 to 2000, gold lost roughly 80% of its real value. It produces no income, pays no dividends, and its price is driven largely by sentiment and macroeconomic fear. A small allocation as portfolio insurance is defensible. A large allocation is a concentrated bet on a specific macro outcome.

Glide Paths: Should Your Allocation Change Over Time?

So far we've talked about static allocations—fixed percentages held for the entire retirement. But there's a strong argument that your allocation should change over time. The question is: in which direction?

The Traditional Glide Path

The conventional approach is to start with a moderate equity allocation and gradually shift toward bonds as you age. This is what target-date retirement funds do. The logic is intuitive: as you get older, you have less time to recover from a market crash, so you should take less risk.

The Rising Equity Glide Path

Research by Wade Pfau and Michael Kitces suggests the opposite approach may actually work better: start retirement with a more conservative allocation (around 30–40% stocks) and gradually increase your equity percentage over time, reaching 60–70% stocks by late retirement.

This sounds counterintuitive, but the reasoning is sound. The biggest threat to a retirement portfolio is sequence of returns risk—a bad market in the early years, when the portfolio is largest relative to withdrawals. By holding fewer stocks in those critical early years, you reduce the damage that an early bear market can inflict. By the time you've shifted to a higher equity allocation, your remaining time horizon is shorter and your portfolio has (hopefully) weathered the most dangerous period.

The early years of retirement matter most because that's when your portfolio is most vulnerable. A 30% market drop in year 2 of a 30-year retirement is devastating. The same drop in year 25, when you've already had decades of withdrawals, matters far less in absolute dollar terms. This asymmetry is why the rising equity glide path can improve outcomes even though it seems to violate conventional wisdom.

Beyond Allocation: Flexible Spending

It's worth noting that asset allocation is only half the equation. How you withdraw matters just as much as how you invest. A rigid 4% inflation-adjusted withdrawal from a moderate portfolio will underperform a flexible withdrawal strategy from the same portfolio.

Strategies like Guyton-Klinger guardrails or the Vanguard Dynamic Spending method adjust withdrawals based on portfolio performance. When markets are up, you spend a bit more. When they're down, you tighten your belt. This flexibility can boost success rates by 5–10 percentage points at any allocation, effectively turning a marginal allocation into a solid one.

The combination of a thoughtful asset allocation and a flexible withdrawal strategy is more powerful than either one alone.

Finding Your Allocation

There is no single “best” asset allocation for retirement. The right answer depends on your withdrawal rate, your time horizon, your other income sources (Social Security, pensions), your risk tolerance, and your ability to cut spending when markets decline.

But the data offers some clear guideposts:

Don't be too conservative. For retirements lasting 25+ years, you almost certainly need at least 50% in equities. Going below that doesn't reduce risk in any meaningful sense—it just trades one type of risk (volatility) for another (portfolio depletion).
The sweet spot for most retirees is between 50% and 80% stocks. Within this range, the success rates are broadly similar, and you're mostly trading off between higher median wealth and a smoother ride.
Consider a glide path. A static allocation is fine, but dynamically adjusting—especially starting more conservatively to mitigate sequence risk—can meaningfully improve outcomes.
Use cash strategically. One to two years of expenses as a withdrawal buffer is sensible. Beyond that, you're likely hurting your long-term success.
Pair allocation with flexible spending. The best allocation with a rigid withdrawal strategy will underperform a decent allocation with a smart withdrawal strategy.

The “subtract your age from 100” rule gets one thing right: younger retirees should generally hold more stocks. But it gets the magnitude wrong for most people, and it completely ignores the interplay between allocation, withdrawal rate, and time horizon that ultimately determines whether your money outlasts you.

The best way to understand how allocation affects your specific situation is to test it. The FIREwiz retirement simulator lets you adjust your stock, bond, cash, and gold allocations and immediately see how they affect your success rate, risk metrics, and projected spending across every historical scenario from 1928 to 2023. Try a few different mixes and see what the data tells you—it's almost certainly not what conventional wisdom predicts.