The 60/40 Portfolio: A Regime-Dependent Average, Not a Law of Nature
What if the classic 60/40 portfolio isn't timeless wisdom, but just one regime among many?
Most investors hold something close to 60% equities and 40% bonds. The logic is simple: equities provide growth, bonds provide safety, and the mix has delivered decent returns with manageable drawdowns. But when we look under the hood across nearly a century of data, a highly unstable picture emerges.
All returns are monthly excess returns (above the risk-free rate), annualized. Drawdowns are maximum peak-to-trough. Weights are unconstrained optimal allocations. Data from Shiller, FRED, CMO (gold), and Bloomberg (oil).
Note: All allocations are unconstrained mean-variance optimal. Real-world portfolios would apply leverage, concentration, and shorting limits. Extreme weights illustrate regime instability rather than actionable advice.
The Full-Sample Case for 60/40
Over the entire 1934–2026 period, the optimizer agrees: 55% equities, 45% bonds.
Stocks & Bonds (1934–2026)
| Asset | Excess Return | Volatility | Sharpe | Max Drawdown | Weight |
|---|---|---|---|---|---|
| Stocks | 8.1% | 12.9% | 0.63 | −53.1% | 55% |
| Bonds | 1.4% | 5.7% | 0.25 | −49.2% | 45% |
| Portfolio | 8.8% | 7.6% | 1.15 | −23.8% | — |
Risk-free rate: 3.46% | Kelly leverage (K): 8.7
This looks reasonable. A 1.15 Sharpe, a −24% worst drawdown. It's the bedrock of modern portfolio theory. But this full-sample average hides enormous variation.
Adding Gold: The Fiat Era Picture
Gold was price-suppressed before 1971 (dollar pegged, not freely convertible). Using CMO data from 1971 onwards, the picture shifts:
Stocks, Bonds & Gold (1971–2026)
| Asset | Excess Return | Volatility | Sharpe | Max Drawdown | Weight |
|---|---|---|---|---|---|
| Stocks | 7.0% | 12.7% | 0.55 | −53.1% | 40% |
| Bonds | 1.9% | 6.9% | 0.27 | −40.5% | 38% |
| Gold | 5.9% | 16.5% | 0.36 | −90.9% | 22% |
| Portfolio | 9.5% | 6.6% | 1.45 | −17.0% | — |
Risk-free rate: 4.45% | Kelly leverage (K): 10.8
Adding gold improves the portfolio: higher returns, lower drawdowns, and the optimizer gives it a 22% weight despite a near-total wipeout (−91%) at one point. The diversification benefit is real—gold is uncorrelated with both stocks (−0.02) and bonds (−0.11).
Adding Oil: More Diversification, More Volatility
Oil total return data from Bloomberg, 1991 onwards:
Stocks, Bonds, Gold & Oil (1991–2026)
| Asset | Excess Return | Volatility | Sharpe | Max Drawdown | Weight |
|---|---|---|---|---|---|
| Stocks | 8.7% | 12.4% | 0.70 | −53.1% | 30% |
| Bonds | 2.4% | 6.2% | 0.39 | −29.8% | 44% |
| Gold | 5.8% | 12.2% | 0.48 | −55.2% | 19% |
| Oil | 9.2% | 25.8% | 0.36 | −90.0% | 7% |
| Portfolio | 8.1% | 5.1% | 1.60 | −15.0% | — |
Risk-free rate: 2.58% | Kelly leverage (K): 20.6
Oil earns a small allocation (7%) because its volatility is extreme—even holding the 6-month contract, oil suffered a −90% drawdown (and the 1-month contract briefly went negative in 2020). The portfolio improves modestly, but the marginal benefit of each new asset is shrinking.
The Problem: Regime Instability
The full-sample weights look sensible. But investors don't live in the full sample. They live through individual decades. And when we split the data into roughly 10-year periods, the optimal weights become dramatically different.
Stocks & Bonds by Decade (since 1934)
| Period | Stock Weight | Bond Weight | Portfolio Sharpe | Max DD | Kelly K |
|---|---|---|---|---|---|
| 1934–44 | 0% | 100% | 5.20 | −2.4% | 806 |
| 1944–54 | 11% | 89% | 2.32 | −2.6% | 100 |
| 1954–64 | 78% | 22% | 1.51 | −16.0% | 14 |
| 1964–74 | Short 22% | Short 78% | 1.46 | −13.8% | −7 |
| 1975–85 | 305% | Short 205% | 0.97 | −60.1% | 2 |
| 1985–95 | 35% | 65% | 1.99 | −8.5% | 16 |
| 1995–05 | 33% | 67% | 1.52 | −5.5% | 15 |
| 2005–15 | 30% | 70% | 1.22 | −9.3% | 19 |
| 2016–26 | 142% | Short 42% | 1.15 | −30.1% | 6 |
The "optimal" stock weight ranges from 0% to 305%, with bonds as high as 100% long to 78% short. The portfolio required shorting bonds in the 1970s and 2010s, and levering equities 3-to-1 in the 1980s. No real-world investor would follow these weights—and that's precisely the point. The data is telling us that the optimal stock/bond mix is completely regime-dependent.
Adding Gold (since 1971)
| Period | Stock Weight | Bond Weight | Gold Weight | Portfolio Sharpe | Max DD | Kelly K |
|---|---|---|---|---|---|---|
| 1971–82 | 142% | Short 1,594% | 1,552% | —* | −100% | 0.2 |
| 1982–93 | 36% | 102% | Short 38% | 2.10 | −15.9% | 11 |
| 1993–04 | 40% | 72% | Short 12% | 1.50 | −8.4% | 13 |
| 2004–15 | 26% | 53% | 22% | 1.54 | −11.6% | 25 |
| 2015–26 | 59% | Short 28% | 69% | 1.65 | −15.1% | 13 |
The 1971–82 portfolio had absurd weights driven by gold's 19% excess return during the inflationary crisis. Realistic constraints would be necessary.
Gold's weight swings from −38% to +1,552%. The 1970s make gold essential; the 1980s–90s make it a portfolio drag. The 2015–26 period gives gold a 69% weight as bonds turn negative.
Adding Oil (since 1991)
| Period | Stock Weight | Bond Weight | Gold Weight | Oil Weight | Portfolio Sharpe | Max DD | Kelly K |
|---|---|---|---|---|---|---|---|
| 1991–03 | 31% | 77% | Short 25% | 17% | 1.89 | −12.5% | 17 |
| 2003–14 | 25% | 45% | 24% | 6% | 1.66 | −13.1% | 25 |
| 2014–26 | 53% | Short 8% | 55% | 0% | 1.57 | −14.1% | 14 |
Even with four assets, the weights remain unstable. The 2014–26 period shorts bonds, gives gold 55%, and nearly eliminates oil. Every decade demands a different portfolio.
The Core Insight
The 60/40 portfolio is not a law of nature. It is the average of many incompatible regimes:
| Regime | Era | Required Portfolio |
|---|---|---|
| Financial repression | 1934–54 | Nearly 100% bonds |
| Post-war growth | 1954–64 | 78% stocks |
| Inflation crisis | 1964–82 | Short bonds, long gold |
| Great moderation | 1982–00 | Balanced 60/40 |
| ZIRP/QE era | 2000–15 | Heavy bonds |
| Post-QE inflation | 2015–26 | Long gold, short bonds |
A static allocation works by accident when the future resembles the average past. When it doesn't—as in the 1970s or the 2020s—it fails.
What Comes Next?
The instability of long-only weights points toward a need for tactical signals—something that can adjust exposure based on the current regime rather than hoping the long-run average holds. In the next section, we examine carry-based strategies that do exactly that.
Data sources: Robert Shiller (equity, bond total returns), FRED (CPI, risk-free rate), Commodity Markets Outlook (gold before 1971), Bloomberg (oil, gold futures since 1991). Kelly leverage K = μ/σ² represents the optimal fraction of capital to bet given the risk-return profile.*
Updated Futures Comparison Table (as of late May 2026)
Standard & Mini/Micro Contracts
| Asset | Contract | Size | Notional Value (approx.) | Tick Value | Initial Margin (approx.) | Daily Volume (typical) | Open Interest | Notes |
|---|---|---|---|---|---|---|---|---|
| Equity | ES (E-mini) | $50 × S&P 500 Index | ~$377,000 (at ~7540) | $12.50 | $24,000 – $26,500 | 1.0 – 2.0+ million | Very High | Benchmark contract |
| Equity | MES (Micro) | $5 × S&P 500 Index (1/10th) | ~$37,700 | $1.25 | $2,400 – $2,700 | Hundreds of thousands | High | Excellent for smaller sizing |
| Notes | ZN (10y) | $100,000 face value | ~$110,000 (at ~110) | $15.625 | $2,000 – $2,300 | 800k – 1.5+ million | Very High | Highest liquidity Treasury future |
| Gold | GC | 100 troy oz | ~$452,000 (at ~$4520/oz) | $10.00 | $30,000 – $36,000 | 100k – 300k | High | Global benchmark |
| Gold | MGC (Micro) | 10 troy oz (1/10th) | ~$45,200 | $1.00 | $3,000 – $3,500 | Moderate (tens of k) | Good | Popular smaller alternative |
| Oil | CL (WTI) | 1,000 barrels | ~$92,000 (at ~$92/bbl) | $10.00 | $12,000 – $13,000 | 300k – 1M+ | 250k – 400k | Most liquid energy contract |
| Oil | MCL (Micro) | 100 barrels (1/10th) | ~$9,200 | $1.00 | $1,200 – $1,500 | Tens of thousands | Moderate | Good for precise/smaller risk |
| Copper | HG | 25,000 pounds | ~$162,500 (at ~$6.50/lb) | $12.50 | $12,000 – $14,000 | 30k – 60k+ | 140k – 180k | Major industrial metal benchmark |
| Copper | MHG (Micro) | 2,500 pounds (1/10th) | ~$16,250 | $1.25 | $1,200 – $1,500 | Low to moderate (thousands) | Growing | Good for smaller accounts / precision hedging |
Margin notes:
- Margins are exchange-set (CME) and fluctuate with volatility. Figures above are approximate initial (speculative) margins. Maintenance margins are usually 10-20% lower.
- Many brokers offer lower day-trading margins (e.g., $400–$500 for ES/MES, $300 for ZN).
- ZN has exceptionally low margin relative to notional — one of the most capital-efficient contracts.
Oil Rolling Practices (Most Delicate Among the Four)
Oil (CL) is by far the most sensitive to rolling mechanics due to its strong tendency toward backwardation (near-term prices > longer-dated) or contango, and because physical delivery/ storage costs create meaningful roll yield.
Common professional approaches:
- Front-month roll (most common for signals/backtests): Roll from the expiring front month into the next active contract 5–10 days before expiry (or first notice day) to avoid delivery risk and liquidity drop-off.
- Constant maturity / continuous contract: Many systematic traders use a weighted roll (e.g., gradually shifting from CL1 to CL2 over several days) or a fixed tenor like "CL 2nd month" to reduce noise.
- Calendar spread awareness: Monitor the CL1-CL2 or CL6 spread closely. In backwardation (common in tight supply), rolling long positions captures positive roll yield. In contango, it creates drag.
- Avoid last few days: Liquidity dries up and basis can become erratic near expiry.
- Micro (MCL): Same logic but with smaller impact per contract — useful when scaling positions precisely around roll dates.
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