Richard Golian

1995-born. Charles University alum. Head of Performance at Mixit. 10+ years in marketing and data.

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CAPE Ratio: Why Today's Stock Market Looks Like the Dot-com Bubble

CAPE ratio and dotcom bubble parallel
Richard Golian
Richard Golian · 2 315 reads
Hi, I am Richard. On this blog I share my thoughts, not investment advice. This is not a recommendation to buy or sell securities.
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Do you know what the Cyclically Adjusted Price-to-Earnings Ratio (CAPE) is? If not, you probably should. Right now, we are at levels reminiscent of the dot-com bubble at the turn of the millennium.

Shiller P/E ratio
Cyclically Adjusted Price-to-Earnings Ratio (CAPE) for the S&P 500: 1871-2025

CAPE, also known as Shiller P/E (developed by Nobel laureate Robert Shiller of Yale University), is a way to determine whether stocks are expensive or cheap. It works by comparing the price of stocks in the market to the average earnings of companies over the past 10 years, adjusted for inflation. Think of it as a tool that smooths out short-term fluctuations and gives us a long-term perspective on whether the market is overvalued (too expensive) or undervalued (cheap). If CAPE is high, it suggests that stocks might be overpriced, reducing the likelihood of high investment returns in the future. The only exception would be if companies’ earnings were to grow dramatically in the upcoming years — far more dramatically than what we saw even during the rise of the internet, one of the biggest technological revolutions in history.

The Story of the Dot-com Bubble

In the 1990s, the internet emerged as a revolutionary technology that promised unlimited possibilities. Startups with vague business models but promising names began to achieve billion-dollar valuations, often without generating real profits. Investors, driven by optimism and the fear of missing out, poured money into any company with ".com" in its name.

At the height of the dot-com bubble, the CAPE for the S&P 500 reached 44.2, the highest figure in modern history. This indicator suggested that the market was extremely overvalued. When investors realised that many of these companies would never be profitable, the sell-off began. By 2002, the Nasdaq index had dropped by more than 75%, and many internet companies had disappeared. For those who invested at the height of the bubble in 2000, it took more than a decade for their investments to regain the same real value. This prolonged recovery was not only due to falling prices but also the impact of inflation, which further eroded the actual value of invested funds.

February 2025

Today, CAPE for the S&P 500 sits at around 38, significantly above the historical average of approximately 16-17.

History does not replay itself, but its parallels cannot be ignored.

Disclaimer

This article is intended for informational and educational purposes only. It does not constitute financial advice, a recommendation to buy or sell any securities, or a guarantee of future market performance. The views expressed are solely those of the author, who may also be an investor. Investing in financial markets involves risk, and each reader should make their own decisions independently and, if necessary, consult with a licensed professional.

Sources

Robert Shiller, creator of the CAPE ratio and Nobel laureate in economics: Yale University, Department of Economics

Summary

The CAPE ratio today is near 38. During the dot-com bubble, it peaked at 44. The historical average is 16-17. This article draws the parallels — and explains why ignoring them is a decision, not an oversight.

Common questions on this article's topic

What is the CAPE ratio?
The CAPE ratio — Cyclically Adjusted Price-to-Earnings, also known as the Shiller P/E — was developed by Nobel laureate Robert Shiller of Yale University. It compares the current price of stocks to the average of company earnings over the past 10 years, adjusted for inflation. By smoothing out short-term fluctuations, it provides a long-term perspective on whether the market is overvalued or undervalued.
What was the CAPE ratio during the dot-com bubble?
At the peak of the dot-com bubble in December 1999, the CAPE for the S&P 500 reached 44.2 — the highest figure in modern history. This extreme overvaluation preceded a crash in which the Nasdaq index fell by more than 77% by October 2002. For investors who bought at the peak, it took more than a decade to recover the real, inflation-adjusted value of their investments.
What is the CAPE ratio today and what does it signal?
As described in the article, the CAPE for the S&P 500 sat at around 38 in early 2025 — significantly above the historical average of approximately 16 to 17. This level suggests that stocks may be overpriced relative to long-term earnings. The only scenario in which such valuations would be justified is if corporate earnings were to grow far more dramatically than even the internet revolution produced.
What happened during the dot-com bubble?
In the 1990s, the internet emerged as a revolutionary technology. Startups with vague business models achieved billion-dollar valuations without generating real profits. Investors, driven by optimism and fear of missing out, poured money into any company with .com in its name. When the market realised that many of these companies would never be profitable, the sell-off began. The Nasdaq dropped by more than 77% and many internet companies disappeared entirely.
Does a high CAPE ratio guarantee a market crash?
No. A high CAPE ratio signals that stocks are expensive relative to historical earnings, which reduces the likelihood of high returns in the future — but it does not predict the exact timing of a correction. As noted in the article, history does not replay itself, but its parallels cannot be ignored. A high CAPE means the margin of safety is thin and the risk of a significant correction is elevated.
How can the CAPE ratio help individual investors?
CAPE provides context that short-term metrics cannot. When CAPE is far above its historical average, it suggests that optimism — rather than fundamentals — may be driving prices. This does not mean investors should sell everything, but it may warrant caution: reducing exposure, increasing cash allocation, or being more selective about when and what to buy. In the article, the current CAPE level is presented as a signal that deserves serious attention.
Richard Golian

If you have any thoughts, questions, or feedback, feel free to drop me a message at mail@richardgolian.com.

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