High U.S. stock valuations signal lower future returns, but the risk is concentrated in a handful of growth giants rather than the broader global market.

The Weight of High Valuations

Investors are increasingly uneasy about high stock market valuations, and to an extent, that concern is mathematically justified. In the world of finance, the price you pay determines the return you get. When valuations are high, expected future returns are lower. These lower returns can manifest in two ways: a slow, grinding period of stagnation over many years, or a swift and painful market correction. Either way, high valuations represent a headwind for long-term wealth accumulation.

The Shiller cyclically adjusted price-earnings (CAPE) ratio—which compares stock prices to smoothed ten-year real earnings—is a reliable, if noisy, barometer for this risk. Historically, CAPE peaks in the United States in 1929 and 1999 preceded major crashes. Today, valuations are hovering around levels seen just before the Great Depression. While this does not guarantee a crash tomorrow, the Shiller earnings yield suggests a real expected return of only about 3% for the S&P 500. For an investor used to the double-digit windfalls of the last decade, this is a sobering projection.

The Concentration of Risk

However, declaring the entire market 'overvalued' misses critical nuance. The perceived expensiveness of the U.S. market is being driven by a remarkably small handful of the largest companies—the so-called 'Magnificent Seven,' including Apple, Microsoft, Nvidia, and Tesla. When you strip away these high-flying growth giants and look at the market through different lenses, such as the price-to-book ratio, the picture changes. The broader market is expensive relative to history, but it is not nearly as stretched as the headline indices suggest.

This concentration creates a divergence between growth and value stocks. Value stocks—those with low prices relative to their fundamentals—do not look particularly expensive right now. History shows that during periods when the broader market struggled due to high starting valuations, value stocks often provided a necessary lifeline. For example, during the 'lost decade' ending in 2010, the S&P 500 lost an annualized 0.31% and the NASDAQ 100 plummeted by nearly 8% annually. Meanwhile, value stocks returned a positive 4.56% per year, illustrating that 'the market' is rarely a monolith.

Lessons from the Lost Decades

The most extreme examples of valuation risk come from periods of high inflation or regional bubbles. In December 1968, U.S. investors entered what would become the worst time to retire in market history. Over the next 16 years, the S&P 500 appeared to grow at 7.24% annually, but inflation ran at 7.22%, meaning investors gained virtually no purchasing power. Large-cap growth stocks fared even worse, actually losing purchasing power. In contrast, value stocks returned over 12% annually during that same period, significantly outperforming the broader market.

Japan provides an even more cautionary tale. Following the 'outright ridiculous' valuations of 1990, the Japanese market entered a slump it is still recovering from three decades later. From 1990 through 2023, the broader Japanese market delivered a meager 1.22% annualized return, while growth stocks actually lost money. Yet, even in this environment, Japanese value stocks returned 4.27% annually. The lesson is clear: even when a national market is underwater, specific factors like value can still offer a path to positive real returns.

The Global Perspective

Beyond the internal dynamics of the U.S. market, investors must also consider geography. The U.S. is not the world. While domestic stocks look invincible after years of dominance, much of those excess returns have been driven by rising valuations rather than just earnings growth. This has led many to fall into 'rear-view mirror bias,' believing that past performance will continue indefinitely without accounting for the current price of admission.

International developed and emerging markets currently trade at much more attractive valuations than the United States. Because their starting prices are lower, their expected future returns are correspondingly higher. A globally diversified investor who tilts away from expensive U.S. growth stocks toward cheaper international equities and domestic value stocks has far fewer reasons to worry about a market-wide collapse. By spreading exposure across different regions and risk factors, the impact of a correction in the most expensive sectors is significantly mitigated.

The Fallacy of Market Timing

While the data suggests that shifting toward value and international stocks is prudent, this should not be mistaken for an invitation to time the market. Identifying that valuations are high is one thing; predicting when they will revert to the mean is another entirely. Timing strategies based on valuation ratios rarely generate reliably positive excess returns because they are highly sensitive to specific time periods and often result in missing the market's best days.

The most effective approach is not to jump in and out of the market based on the CAPE ratio, but to build a portfolio that is structurally diversified from the start. By maintaining consistent exposure to multiple priced risks—including value, small-cap, and international stocks—investors can capture growth where it occurs without being over-leveraged to the most expensive and vulnerable segments of the U.S. market. High valuations are a signal to diversify, not a signal to exit.