60/40, Target-Date Funds, or 100% Stocks Forever? They're Solving Different Problems.

They Are Solving Different Problems

The 60/40 portfolio, Vanguard's target-date fund glide path, and Cederburg's "100% stocks forever" research are the three dominant positions in the asset allocation debate. They generate endless arguments on Reddit, Twitter, and personal finance blogs. But most of those arguments miss a crucial point: these three approaches are not competing answers to the same question.

• 60/40 is trying to balance growth with stability for investors who need lower volatility.
• Vanguard's target-date glide path is trying to be a scalable default for the broad population of retirement savers.
• Cederburg's all-equity research is asking: if you model lifetime saving and spending using a large international historical dataset, what allocation maximizes expected retirement utility?

Those are related questions, but they are not identical. The right allocation depends on which problem you are actually solving.

The Case for 60/40

A CFA Institute historical study using the Dimson-Marsh-Staunton database across 35 countries found that 60/40 delivered positive real returns with lower volatility and smaller drawdowns than all-equity portfolios. That is the core value proposition: growth with damage control.

The caveat: stock-bond correlation has not been consistently negative over history. In 2022, both stocks and bonds fell together. Vanguard argues this was unusual and that bonds resumed their diversifying role in 2023, but the episode shows that 60/40 is not a guaranteed shock absorber.

Who 60/40 is for

• People near or in retirement who are drawing from the portfolio
• Investors with low risk tolerance or low ability to withstand large drawdowns
• Households that prioritize reducing portfolio violence over maximizing terminal wealth

Who 60/40 is not for

• Young accumulators with 20+ year horizons and high savings rates
• Investors who treat it as a universal rule rather than a specific solution for specific people

The Case for Vanguard Target-Date Funds

Vanguard's target-date funds are explicitly designed as a broad default, not a bespoke optimum. Vanguard says TDFs help investors build diversified portfolios, simplify the process, and serve as sensible defaults inside retirement plans.

The standard glide path starts around 90% equity at age 25, declines to 50% at age 65, and lands around 30% by age 72. The assumed participant saves 8.8-12% of salary and targets ~79% of ending salary as retirement income. Vanguard is transparent that these are baseline assumptions, and that people outside the broad middle may need advice or personalization.

Who target-date funds are for

• The broad middle of investors who want a one-fund, set-and-forget retirement solution
• Less-engaged savers who benefit from automation and will not rebalance manually
• Tax-advantaged retirement accounts (401k, IRA) where the structure is most appropriate

Who target-date funds are not for

• Investors with unusual risk tolerance, pensions, high savings rates, or strong bequest goals
• Taxable accounts (the SEC's 2025 action against Vanguard over tax consequences for retail TDF holders is a reminder)
• Investors who want to hold meaningfully more equity than the glide path allows

The Case for All-Equity (Cederburg)

The "Beyond the Status Quo" working paper by Anarkulova, Cederburg, and O'Doherty is the most provocative contribution to this debate in years. Using a developed-market dataset spanning 38 countries and nearly 2,500 years of country-month return observations, their lifecycle simulations find that a globally diversified all-equity allocation beats stock-bond and age-based strategies on wealth at retirement, retirement consumption, preservation of savings, and bequests. The optimal policy in the paper is roughly one-third domestic stocks and two-thirds international stocks with essentially no fixed income across the life cycle, so the takeaway is global diversification, not a 100% U.S. equity portfolio.

The companion finding on long-horizon risk is what makes the paper so challenging: estimated 30-year real loss probabilities were about 13% for domestic stocks, 27% for bonds, and 37% for bills, versus only 4% for international stocks. That undermines the assumption that bonds are the "safe" asset over lifetime horizons.

But the authors themselves acknowledge the key limitation. In a Brandes Center discussion, Cederburg said that if investors panic and sell in crashes, "all of this falls apart." Anarkulova explicitly said investors likely to do that may be better off with 80/20 or 90/10 rather than 100/0.

Who all-equity is for

• Very disciplined investors with high risk capacity and proven ability to hold through severe drawdowns
• Long horizons (20+ years to retirement, or in early accumulation)
• High savings rates and flexible spending in retirement
• Investors who understand this means global equity, not just U.S. large-cap

Who all-equity is not for

• People who will sell during crashes (the paper's results assume perfect discipline)
• People near retirement who need a stable withdrawal base in the next 5-10 years
• People who sleep better with meaningful fixed income (that is not weakness; it is self-awareness)

The Real Decision Framework

The debate is not "which is objectively best." It is "which problem am I solving?" Three questions clarify the answer:

For most readers, the Vanguard target-date fund is the practical default. It does not maximize expected wealth; it maximizes the chance the average household actually sticks with a diversified, low-cost, automated allocation through a full career.

For sophisticated investors with high savings rates, strong job stability, and proven discipline through downturns, moving toward 80/20 or 90/10 global equity is defensible and supported by Cederburg's research. Going to 100/0 is the theoretical optimum in the model but requires perfect execution that most humans cannot deliver.

For people near or in retirement, or those with genuinely low risk capacity, 60/40 or a more conservative allocation still does its job: it cushions sequence-of-returns risk during the years when a deep drawdown is hardest to recover from.

Model your own allocation and see how it performs across thousands of market scenarios in Summitward's retirement simulation. The Monte Carlo engine runs 5,000 paths with your specific age, spending, Social Security, and allocation.

Frequently Asked Questions

Is 60/40 dead?

No. 60/40 had a historically bad year in 2022 when stocks and bonds fell together, but that was unusual. CFA Institute's 35-country historical study shows 60/40 has delivered positive real returns with lower drawdowns than all-equity. It is the wrong tool for accumulators with long horizons and the right tool for retirees managing sequence risk.

Does the Cederburg paper prove I should hold 100% stocks?

The paper shows that a globally diversified (1/3 domestic, 2/3 international) all-equity allocation maximizes expected lifetime utility in their model. But the authors themselves say this falls apart if investors panic-sell, and suggest 80/20 or 90/10 as more realistic. It is a working paper, not a commandment.

Should I use a target-date fund?

For most people, yes. TDFs are the strongest one-fund default: globally diversified, low-cost, automatically rebalanced, and age-appropriate. They are designed for the broad middle of retirement savers. Use them in tax-advantaged accounts.

What about bonds as an inflation risk?

Cederburg's companion paper found 30-year real loss probabilities of 27% for bonds and 37% for bills, versus 4% for international stocks and 13% for domestic stocks. That challenges the assumption that bonds are "safe" over lifetime horizons. But bonds still reduce short-term volatility, which matters for retirees drawing from their portfolio.

Key Takeaways

• 60/40, target-date, and all-equity solve different problems. Do not compare them as if they answer the same question. Match the approach to your time horizon, risk capacity, and behavioral discipline.
• Target-date funds are the right default for most people. Not because they maximize wealth, but because they maximize the probability that a real human sticks with a reasonable plan.
• The Cederburg result is global, not U.S.-only. The optimal policy is roughly 1/3 domestic, 2/3 international equity.
• All-equity only works if you actually hold. The authors themselves say 80/20 or 90/10 may be more realistic for investors who might panic-sell.
• 60/40 is not dead. It is the right tool for people near retirement, drawing from the portfolio, or with genuinely low risk capacity.
• Behavior matters more than allocation. An 80/20 portfolio you hold through a crash beats a 100/0 portfolio you sell at the bottom.

Related Guides

• Modern Portfolio Theory for Real Life — the framework that says portfolio variance depends on covariances, with a marginal-fund-test calculator and a “correlations go to one” supplement
• You Have One Household Portfolio — the practical companion: how to aggregate accounts, handle asset location, and use a Household X-Ray calculator to see your true total allocation
• Stocks Usually Win. "Usually" Is Not a Financial Plan. — the historical evidence (Arnott chart, McQuarrie reconstruction) behind why some allocations choose to hedge equity-premium-failure risk with bonds even at the cost of lower expected returns
• The Case for Global Equity Diversification — central to the Cederburg result (2/3 international)
• Safe Withdrawal Rate — how allocation affects withdrawal sustainability
• Sequence of Returns Risk — why allocation matters most at the transition to retirement
• Lifecycle Asset Allocation — the academic framework behind glide paths
• Lump Sum vs. DCA — behavioral discipline in a different context
• Do You Need Managed Futures? — a fourth bucket beyond stocks/bonds/cash, with a sleeve decomposition calculator and an honest review of who it is and isn’t for
• Do You Need Return Stacking? — the capital-efficiency angle: stacked products (NTSX, RSSB, SPLS, RSST) let you hold both stocks AND bonds AND a diversifier from the same dollar