CAPE Ratio Explained: Is the Stock Market Overpriced?

Every few years, someone on financial Twitter — or your brother-in-law at Thanksgiving — declares that the stock market is wildly overvalued and a crash is imminent. They usually cite one number: the CAPE ratio. Then, just as confidently, someone else says CAPE is a broken relic from a different era and you should ignore it entirely.

Both of those people are probably wrong. The truth about the CAPE ratio is more interesting than either camp admits — and understanding it properly will genuinely change how you think about long-term investing.

What Is the CAPE Ratio, Exactly?

CAPE stands for Cyclically Adjusted Price-to-Earnings ratio. It's also called the Shiller P/E, named after Yale economist Robert Shiller, who — along with John Campbell — popularized it in a 1988 paper and used it to call the dot-com bubble before it burst. He won the Nobel Prize in Economics in 2013, partly for this work.

Here's the plain-English version of what it measures: how expensive the stock market is relative to the earnings companies actually produce.

A standard P/E ratio takes the current price of a stock (or an index) and divides it by last year's earnings. Simple enough. The problem is that corporate earnings are noisy. One bad year — a recession, a pandemic, an oil shock — can crater reported earnings and make the P/E look artificially high. One boom year can do the opposite. You're comparing today's price to a single data point that might be totally unrepresentative.

Shiller's fix was elegant. Instead of using one year of earnings, he uses ten years of earnings, adjusted for inflation. That smooths out the boom-bust cycle in corporate profits and gives you a much cleaner picture of whether the market is genuinely expensive or just looks expensive because earnings temporarily collapsed.

The formula, if you want it:

CAPE = Current S&P 500 Price ÷ Average of Last 10 Years of Inflation-Adjusted Earnings

The longer average essentially removes the distortion from any single economic cycle — which is exactly why Shiller called it cyclically adjusted.

Why Should You Care? The Wallet Version

The CAPE ratio isn't an academic curiosity. It has a documented relationship — imperfect but real — with future stock market returns.

Here's the intuition. When you buy stocks at a high CAPE, you're paying a lot for each dollar of earnings the market generates. You're betting on continued growth, continued optimism, or both. When that CAPE is low, you're getting more earnings per dollar spent — a bigger cushion against disappointment.

Multiple decades of data bear this out. When CAPE has been low (say, below 15), the stock market's returns over the following ten years have generally been strong — sometimes spectacular. When CAPE has been very high (above 30), forward ten-year returns have historically been much more modest, and in some cases negative in real terms.

To put a number on it: research from Vanguard and others has consistently found that the CAPE ratio explains somewhere between 40% and 60% of the variance in ten-year forward returns for the S&P 500. For a single valuation metric, that's impressive. Nothing predicts with certainty — but CAPE beats most alternatives for the long run.

For you as an investor, here's what that means practically: if you're 25 and investing for 40 years, a high current CAPE should give you pause about return expectations, not necessarily cause you to flee equities entirely. If you're 62 and drawing down your portfolio in 8 years, a sky-high CAPE is a more urgent conversation.

The Historical Numbers (and What They Actually Show)

The long-run average CAPE for the S&P 500 — going back to the 1880s — is roughly 17. That's your baseline. Below 17, historically cheap. Well above 17, historically expensive.

Here's how some memorable market moments looked through the CAPE lens:

| Period | Approximate CAPE | What Happened Next |

|---|---|---|

| August 1982 (market bottom) | ~7 | Monster bull market through the 1980s and 1990s |

| December 1999 (dot-com peak) | ~44 | S&P 500 lost ~50% by 2002; lost decade in real terms |

| March 2009 (financial crisis low) | ~13 | Decade-long bull market, one of history's longest |

| January 2018 | ~33 | Modest 2018 correction, then rally — before 2020 crash |

| Early 2022 (pre-rate hike) | ~38–40 | Sharp equity selloff as Fed hiked aggressively |

| As of mid-2026 | ~34–37 (est.) | Ongoing debate — see below |

Sources: Multpl.com, Robert Shiller's online dataset, Federal Reserve data.

The 1999 reading of 44 is the one that still gives analysts nightmares. The market was paying $44 for every $1 of ten-year average earnings — a valuation so stretched that no plausible earnings growth could justify it. Shiller said so publicly. He got ridiculed. Then the Nasdaq fell 78%.

The 2009 reading of 13 was the mirror image. You were getting $1 of smoothed earnings for every $13 invested. That's the kind of price that, historically, produces genuinely excellent long-term returns. Nobody felt good about buying then — the financial system had just nearly collapsed — but the CAPE was screaming that equities were on sale.

The Serious Criticisms (Because There Are Real Ones)

Look, I'd be doing you a disservice if I just cheerled for Shiller P/E without telling you what the critics say. Some of them make fair points.

1. Accounting standards changed. The way companies report earnings today isn't identical to how they did in 1920 or even 1990. Changes in GAAP rules — particularly around write-downs and goodwill — have affected reported earnings. Some analysts argue modern earnings are structurally understated compared to historical norms, which makes the current CAPE look higher than an apples-to-apples comparison would justify.

2. Interest rates matter — a lot. A CAPE of 30 in an era of 1% Treasury yields is a very different beast than a CAPE of 30 when 10-year Treasuries are yielding 5%. When bonds are paying almost nothing, investors are rationally willing to pay more for equity earnings. This is the "Fed model" argument, and it has genuine merit, even if it's also been weaponized to excuse almost any level of stock market excess. The interaction between bond yields and equity valuations is one of the most important dynamics in markets — CAPE doesn't capture it directly.

3. The composition of the S&P 500 has shifted. Today's S&P 500 is dominated by technology and mega-cap growth companies that carry structurally higher P/E multiples because they're asset-light, highly profitable, and scalable. In the 1950s, the index was full of capital-intensive manufacturers and railroads. Comparing the "fair value" CAPE across those two eras may be like comparing apples to something that didn't exist in 1950. Nvidia, for example — whose earnings trajectory has been extraordinary — illustrates just how differently the market can price a company when growth expectations are extreme. (See: Nvidia's Numbers Were Massive. Look Closer.)

4. It's terrible at timing. This one's critical. Shiller P/E has an abysmal short-term track record. The CAPE was above 25 for most of the late 1990s. Anyone who sold in 1996 missed three of the best years in stock market history before the crash finally came. "Expensive" can get more expensive for a very long time.

A Better Way to Think About It

Here's the framing I find most useful: CAPE isn't a light switch — it's a dimmer.

When CAPE is low, the dimmer is turned up. The odds of strong future returns are relatively high. When CAPE is very high, the dimmer is turned down. You're not guaranteed a crash — markets can stay elevated for years — but your expected forward returns are lower, and your risk of a painful drawdown is higher.

That's meaningfully different from saying "sell everything." It's useful information for calibrating expectations and thinking about asset allocation. If you were planning to pile into equities right before retirement based on the assumption that historical average returns (about 10% nominal) are a reliable near-term forecast — a high CAPE is a reason to revisit that plan carefully.

One supplementary metric worth pairing CAPE with: the Buffett Indicator, which compares total US stock market capitalization to GDP. It captures a similar concept from a slightly different angle and has been similarly elevated in recent years.

How This Applies in 2026

Without pretending I can see the future, here's the honest situation as of mid-2026: the CAPE ratio for the S&P 500 has been running well above its long-run historical average — in the range of 34–37 by most estimates. That's not dot-com-bubble territory, but it's not cheap either.

This doesn't tell you a crash is coming next month. What it does tell you is that the stock market isn't on sale, and if you're projecting 10–12% annual returns based on past averages, you're probably being optimistic. A reasonable scenario — not a catastrophe, just a mathematical reality — is that returns over the next decade come in meaningfully below that.

There are complicating factors, as there always are. Macro uncertainty has been elevated — questions around trade policy, geopolitical risk, the dollar's trajectory, and how the Federal Reserve manages rates all play into how investors price risk. Understanding these cross-currents matters. Recent moves in Treasury markets have raised fair questions about whether the flight-to-safety assumptions investors have relied on for decades still hold.

For someone investing new money today, none of this means sitting in cash. It means being honest with yourself about return expectations, keeping international diversification on the table (plenty of non-US markets carry far lower CAPEs), and not betting your retirement on the next five years looking like 2009–2021.

CAPE Across Markets: US Isn't the Only Option

One thing the CAPE debate often misses: it doesn't just apply to US stocks. Shiller's methodology has been applied to equity markets worldwide — and the spread between countries can be striking.

| Market | Approximate CAPE (mid-2026 est.) | Interpretation |

|---|---|---|

| United States (S&P 500) | 34–37 | Historically expensive |

| United Kingdom (FTSE All-Share) | 13–16 | Well below historical averages |

| Japan (TOPIX) | 16–19 | Near historical mean |

| Emerging Markets (broad) | 12–15 | Relatively cheap vs. history |

| Germany (DAX) | 17–20 | Near historical mean |

| India (Nifty 50) | 22–26 | Premium to history, but high-growth economy |

Approximate estimates based on available historical Shiller P/E data and analyst compilations. Treat as directional, not precise — individual methodology differences apply.

The US has commanded a valuation premium over most global markets for a long time, partly justified by stronger earnings growth and better shareholder returns. But when that premium stretches far enough, the math of international diversification starts to look genuinely attractive — not just as a risk management move, but as a way to buy earnings more cheaply.

FAQ

What is a good CAPE ratio for the stock market?

There's no single "good" number in isolation, but context helps. The long-run historical average for the US S&P 500 is roughly 17. CAPEs below 15 have historically preceded strong long-term returns. CAPEs above 30 have historically been associated with below-average long-term returns — though not necessarily an immediate crash. Whether a given CAPE is "acceptable" also depends heavily on prevailing interest rates: in a low-rate environment, investors have traditionally been willing to pay higher multiples for equities than they would when bonds are offering meaningful yields.

Why do people call it the Shiller P/E ratio?

Robert Shiller — a Yale economist and Nobel laureate — popularized the cyclically adjusted P/E ratio in an influential 1988 academic paper co-authored with John Campbell. Shiller subsequently built and maintained a public dataset of this metric going back to the 1880s, which made it the go-to long-term valuation benchmark. He became widely known for pointing to dangerously high CAPE readings ahead of the dot-com bust and, later, for warnings before the 2008 housing crisis. The name Shiller P/E has stuck in his honor, even though the underlying concept of smoothing earnings over time predates him.

Can the stock market stay overvalued by CAPE for a long time?

Yes — and this is the CAPE ratio's most significant practical limitation. By multiple measures, US equities have looked "expensive" relative to historical CAPE averages for most of the period since the early 1990s. The market still delivered strong returns through most of that era. What a high CAPE tells you is that expected future returns are lower and the risk of a large drawdown is higher — not that a correction is imminent. Selling based purely on a high CAPE reading in, say, 1996 would have meant missing three of the strongest years in stock market history. CAPE works over 10-year horizons, not 10-month ones.

Does a high CAPE ratio mean I should sell my stocks?

Not necessarily — and for most long-term investors, probably not. What a persistently high CAPE should do is temper your return expectations and prompt you to think about your allocation honestly. If you're decades from retirement, riding out valuation cycles is pretty much the job description of a long-term equity investor. If you're closer to needing the money, a high CAPE is worth factoring into how much equity risk you're carrying — not as a sell signal, but as a reason to make sure your portfolio can survive a meaningful drawdown without forcing you to sell at the worst time. International diversification is worth a serious look when US CAPE is historically elevated and other markets are cheap by comparison.

Is the CAPE ratio broken because of tech stocks?

It's a fair question, and critics have raised it seriously. The S&P 500 today is more concentrated in high-margin, asset-light technology companies than at almost any prior point in index history — and those companies structurally carry higher earnings multiples because their earnings power compounds differently than, say, a steel manufacturer. This almost certainly means the "fair value" CAPE for the modern S&P 500 is higher than the raw 17-ish historical average. But by how much? Nobody agrees. And how you weight mega-cap tech earnings is genuinely tricky — stocks like Nvidia have seen earnings growth so extreme that even the 10-year average may not fairly represent their current earnings power. That cuts both ways, though: extreme earnings growth in one period can mean reversion in another. The answer isn't that CAPE is broken — it's that using it thoughtfully means recognizing the index has changed, and pairing it with other tools rather than treating it as the only word on valuation.