What Is the CAPE Ratio and What Does It Tell Us About Stock Valuations?
The CAPE ratio divides the S&P 500 price by 10 years of inflation-adjusted earnings. It reveals long-term valuation levels by smoothing out business cycle fluctuations. High CAPE has consistently predicted lower 10-year returns — but it is not a timing tool.
Looking for more macro answers?
In this article
The short answer
The standard P/E ratio divides a stock’s price by one year of earnings. The problem is that earnings are highly cyclical — they boom in expansions and collapse in recessions. A stock can look cheap on trailing P/E right before earnings fall off a cliff.
Nobel laureate Robert Shiller designed the CAPE to solve this. By averaging 10 years of inflation-adjusted earnings, the CAPE smooths out the cycle and gives a more stable, long-term view of whether the market is expensive or cheap relative to its earning power.
It’s the financial equivalent of judging a restaurant not by tonight’s meal but by its consistency over the last decade. The CAPE won’t tell you what happens next month — but it tells you a great deal about what to expect over the next decade.
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What the data shows
Using Professor Shiller’s own dataset (Yale, 1881–2026), the CAPE ratio has ranged from a low of approximately 5 in 1921 to a peak near 44 in December 1999 — just before the dot-com crash.
The historical median is approximately 16. Every time the CAPE has exceeded 30, subsequent 10-year real returns have been below the historical average. When the CAPE fell below 10, subsequent 10-year returns were consistently above 10% annualized in real terms. The relationship is not linear — it’s a strong tendency, not a law.
The current CAPE near 38 places the market in the top decile of historical valuations. Based on the 1881–2024 sample, this range has historically been followed by 10-year real returns of approximately 0–4% annualized — well below the long-run average of roughly 6.5% real.
The important exception: the CAPE exceeded 30 in 1997 and stayed elevated for years while the market continued to rise. Investors who sold based solely on CAPE in 1997 missed significant gains before the eventual correction. The CAPE is a measure of expected returns, not a market timing tool.
→ Full study: Real Interest Rates vs CAPE Ratio — Dataset & Analysis
Why it happens — the macro mechanism
The CAPE works because of a fundamental principle: the price you pay determines the return you get. When you buy the market at a high CAPE, you are paying more per unit of future earnings — mathematically, your expected return is lower.
But the CAPE does not exist in a vacuum. Its information content depends on the real interest rate regime.
When real rates are high (1980s), a CAPE of 10 reflects genuinely cheap equities because investors have attractive bond alternatives. When real rates are near zero or negative (2010–2021), a higher CAPE is partially justified because the opportunity cost of holding stocks versus bonds is low.
The Excess CAPE Yield (ECY) — which compares the inverse of the CAPE to the real bond yield — provides a more complete picture. Eco3min’s research on this relationship shows that the tent-shaped dynamic between real rates and CAPE creates distinct valuation regimes that matter far more than the CAPE level in isolation.
The macro regime also affects the E in the ratio. If profit margins are structurally elevated (due to technology, monopolistic concentration, or globalization), the CAPE may overstate expensiveness. If margins are mean-reverting — as they historically have been — then today’s elevated earnings may be the exception, not the norm.
→ Framework: Financial Markets Hub · Valuations & Earnings Dynamics
The CAPE doesn’t tell you what happens next. It tells you what you’re paying for it.
What it means for different economic actors
Long-term investors should use the CAPE to calibrate expectations, not to time entries and exits. A CAPE of 38 does not mean the market will crash — it means the expected 10-year return is lower than usual. Adjusting asset allocation to reflect this — perhaps tilting toward international markets with lower CAPEs, or increasing bond allocation — is a rational response.
Retirees using withdrawal strategies should pay close attention. Starting a retirement drawdown when the CAPE is in the top decile significantly increases the risk of portfolio depletion — the well-documented “sequence of returns” risk. Higher CAPE at retirement warrants a more conservative withdrawal rate.
Institutional investors use the CAPE and ECY as inputs to strategic asset allocation models. It informs how much capital to allocate to equities versus bonds, real assets, or cash, based on where expected returns sit relative to historical norms.
A persistent error is treating the CAPE as a trading signal. Markets can remain “expensive” for years — the CAPE stayed above 25 for most of 2014–2024. The right use is probability and expectation management, not prediction.
Go deeper
📊 Full study: Real Interest Rates vs CAPE Ratio — Complete Analysis (1963–2026)
📁 Datasets: S&P 500 Historical Returns · S&P 500 Price Index
📖 Related: What drives stock market returns over the long run?
Related questions
Frequently asked questions
Is the CAPE ratio broken because markets stay expensive?
Not broken — but potentially undergoing a structural shift. Higher profit margins (driven by tech sector dominance), lower real interest rates, and stock buybacks may justify a permanently higher baseline than the historical average of 17. However, even adjusting for these factors, current levels above 35 remain in the upper range. The predictive power of CAPE for 10-year returns has persisted across every sub-period since 1881.
Does the CAPE work for non-US markets?
Yes. Research by StarCapital and others shows that the CAPE-to-forward-return relationship holds across most developed and emerging markets. European and Japanese markets typically trade at lower CAPEs than the U.S., partly reflecting different sector compositions, growth expectations, and regulatory environments.
What CAPE level represents a good buying opportunity?
Historically, a CAPE below 15 has been followed by above-average 10-year returns with high consistency. Below 10 — which occurs only during severe crises — has produced exceptional returns. However, these opportunities are rare and arrive only when the economic backdrop is genuinely frightening. The last time the U.S. CAPE dipped below 15 was briefly in March 2009.
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Last updated — 14 April 2026