The Bond-Allergy Mistake

Quick definition: Bond-allergy is the belief that stocks always outperform bonds and therefore bonds should be avoided entirely, eliminating a key portfolio stabilizer and forcing investors to hold 100% stocks.

Key Takeaways

• Bonds have returned 4–6% annually historically, underperforming stocks (10%) but with far lower volatility, making them excellent diversifiers.
• Stock-bond correlation is often negative or near-zero; when stocks fall sharply, bonds often rise, providing portfolio ballast.
• 100% stock portfolios experience 40–50% drawdowns periodically, while 60/40 portfolios experience 25–30% drawdowns—a significant difference in emotional sustainability.
• Bonds are not "useless"; they provide a crucial role in reducing portfolio volatility and enabling rebalancing.
• A young investor can hold a higher stock allocation than a retiree, but even young investors benefit from some bond allocation for stability and rebalancing opportunities.

The Source of Bond Allergy

Bond allergies arise from a simple observation: stocks outperform bonds over the long term. From 1926 to 2024 (nearly 100 years of data), U.S. stocks returned roughly 10% annually while long-term U.S. bonds returned roughly 5–6% annually. Stocks doubled the return. If you are investing for 30 or 40 years, why would you ever own a lower-returning asset?

This logic is seductive and almost entirely wrong. It suffers from several fatal flaws. First, it ignores volatility and risk. Second, it ignores the power of diversification. Third, it ignores the rebalancing benefit. Fourth, it ignores behavioral finance and the likelihood of panic-selling an all-stock portfolio during crashes. The bond-allergic investor believes they are being "efficient" by holding 100% stocks, but they are actually exposing themselves to unnecessary risk and the near-certainty of making emotionally-driven mistakes during drawdowns.

Volatility and Risk-Adjusted Returns

Yes, stocks outperform bonds by 4–5% annually on average. But stocks achieve this outperformance through much higher volatility. From 1926 to 2024, stocks had an annualized volatility (standard deviation) of roughly 18%, while bonds had volatility of roughly 6%. Stocks are three times as volatile as bonds.

When you account for this volatility difference, the picture changes. The risk-adjusted return (often measured as the Sharpe ratio—return per unit of risk) of stocks and bonds is much closer than the raw return numbers suggest. Over 100 years, stocks had a Sharpe ratio of about 0.45 (return minus risk-free rate, divided by volatility), while bonds had a Sharpe ratio of about 0.35. Stocks are better on a risk-adjusted basis, but not as dramatically as the raw return numbers suggest.

More importantly, the volatility difference creates different experiences for different investors. An investor with $1 million in 100% stocks experiences portfolio swings of $180,000 per year in normal markets (18% volatility). In a down year, the portfolio might fall by $300,000 or more. An investor with $1 million in a 60/40 portfolio (60% stocks, 40% bonds) experiences portfolio swings of roughly $110,000 per year. In a bad year, the portfolio might fall by $150,000–$200,000. The 60/40 portfolio has only 60% of the volatility of the 100% stock portfolio.

These differences sound academic until they matter. When your 100% stock portfolio falls by $300,000 in a year, your psychological resolve is tested. You begin to question your strategy. You fear it will fall further. You sell to "protect" your remaining capital. A 60/40 investor with a $200,000 decline is more likely to hold firm because they knew this kind of decline was within their expectations.

Stock-Bond Correlation: The True Diversification Benefit

The most powerful argument for owning bonds is not that bonds are great investments (they are not—they underperform stocks). It is that bonds provide diversification. Stocks and bonds have a correlation that is often negative or near-zero, meaning they move in different directions at different times.

Consider the history of stock and bond returns:

1970–1980: Stagflation era. Stocks fell roughly 5% (flat-to-negative returns). Bonds fell more than 10%. Both bad, but stocks were relatively better.

1980–1990: Disinflationary boom. Stocks rose 17% annually, bonds rose 11% annually. Both good, stocks better.

2000–2009: Tech bubble burst and financial crisis. Stocks returned 0% (a disaster). Bonds returned 5–6% annually. Bonds were far better.

2010–2019: Post-crisis recovery and tech boom. Stocks returned 14% annually, bonds returned 3–4% annually. Stocks dominated.

2022: Inflation surge and rate hikes. Stocks fell 18% (S&P 500), bonds fell 13% (aggregate bond index). Both down, but bonds fell less.

Notice the pattern: when stocks crash (2000–2009, 2022), bonds typically fall less or even rise (depending on the type of bonds and whether interest rates are falling). When stocks soar (2010–2019), bonds lag. A portfolio holding both gets:

• Some participation in stock gains (since stocks outperform most of the time)
• Reduced losses during stock crashes (since bonds soften the blow)
• The ability to rebalance and buy stocks low when they crash (because bonds held their value)

Over 100 years of data, a 60/40 portfolio (60% stocks, 40% bonds) had only slightly lower returns than a 100% stock portfolio (8% vs. 10% annually), but with significantly lower volatility and far fewer catastrophic drawdowns. For most investors, this is a better outcome.

The Rebalancing Superpower

Here is a subtle but powerful benefit of owning bonds that bond-allergic investors completely miss: rebalancing.

In a 100% stock portfolio, there is nothing to rebalance. When stocks go up, you are 100% stocks. When stocks go down, you are 100% stocks. You have no mechanism to "buy low" and "sell high."

In a 60/40 portfolio, rebalancing works like this:

• Year 1: Stocks rise 20%, bonds rise 5%. Your portfolio drifts from 60/40 to 65/35. You rebalance by selling some stocks (now expensive) and buying some bonds (now cheap).
• Year 2: Stocks fall 20%, bonds rise 10%. Without rebalancing, your portfolio would drift to 50/50 or worse. With rebalancing, you sell bonds (now expensive) and buy stocks (now cheap).

Over time, this rebalancing—automatically buying low and selling high—adds 0.5–1.5% per year to returns. This is not a gimmick. It is mathematically proven. A 60/40 portfolio with regular rebalancing can outperform a 100% stock portfolio in real-world conditions, despite owning lower-returning bonds, simply because the rebalancing adds value.

A bond-allergic investor who holds 100% stocks never gets this rebalancing benefit. They are exposed to maximum volatility and maximum drawdowns without any of the diversification benefit.

Drawdowns: The Human Reality

Here is where the rubber meets the road. Drawdowns are not theoretical; they happen, and they test your resolve. Consider the historical experience:

100% stock portfolio:

• Average annual volatility: 18%
• Typical decline in a bad year: 15–20%
• Maximum decline in a crisis year (like 2008 or 2022): 40–50%
• Multi-year bear market (like 2000–2002): Decline of 45%+ with a recovery that takes 7+ years

60/40 portfolio:

• Average annual volatility: 11%
• Typical decline in a bad year: 10–15%
• Maximum decline in a crisis year: 25–30%
• Multi-year bear market: Decline of 25–30% with a recovery that takes 4–5 years

The difference is dramatic. A 60/40 investor experiencing a 25–30% decline can tell themselves: "This is within my expectations. Bear markets happen. I will hold." A 100% stock investor experiencing a 40–50% decline is far more likely to panic and sell, locking in losses.

This is not speculation. Research by behavioral economists has shown that investors with all-stock portfolios are significantly more likely to panic-sell during crashes than investors with diversified portfolios. The 100% stock investor, shocked by the magnitude of the decline, concludes something has gone terribly wrong and sells. The 60/40 investor, expecting this kind of volatility, holds steady.

Age and Stock Allocation

There is a grain of truth in the argument that younger investors should hold more stocks than older investors. A 25-year-old has 40+ years until retirement. Market crashes will happen several times during those 40 years, but there is plenty of time for recovery. A 65-year-old, approaching or in retirement, does not have 40 years to recover from a crash. They need more stability.

But this does not justify 100% stocks even for young investors. Here is why:

First, a young investor still experiences psychological pain during crashes, even if they have time to recover. A 30-year-old who sees their $200,000 portfolio drop to $100,000 is not comforted by knowing they have 35 years to recover. They experience real emotional trauma and might abandon their strategy out of fear.

Second, a young investor might need money from their portfolio before retirement (for a home down payment, education, a career transition). An all-stock portfolio that crashes just when they need access to the money is problematic.

Third, young investors who panic-sell during crashes often do not re-enter the market at the right time. They sell in fear near the bottom, move to cash, watch the recovery from the sidelines, and eventually buy back in near the top—missing the biggest returns of the cycle.

A reasonable allocation for a 25-year-old might be 70–80% stocks and 20–30% bonds. This is much more aggressive than a 60/40 portfolio, but it still provides some stability and rebalancing benefit. As they age and approach retirement, they can gradually increase bonds to 40–50%.

For retirees or near-retirees, an all-stock portfolio is often dangerous. A 60/40 or 50/50 allocation is more appropriate because it reduces the risk of being forced to sell stocks at the bottom when market-dependent income is needed.

The Modern Bond Market

One minor benefit of bonds that has improved over time: modern bond yields are higher than they were in the 2010–2020 period. For years, bonds yielded 1–3% annually, making them unattractive relative to stocks. Today (2026), bonds yield 4–5% annually, which is more competitive with historical norms. This has restored some appeal to bonds and makes them a more attractive portfolio component than they were during the post-crisis decade.

Process

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The eighth and final mistake is tracking-error anxiety, where investors worry excessively about how their portfolio differs from market benchmarks and make constant adjustments to match indexes.