Introduction: the question nobody asked you
You have probably heard the familiar lines from banks, brokers or financial salespeople: the market still has upside, diversification remains the best strategy, and it is always a good time to invest.
But when was the last time somebody showed you the CAPE ratio before selling you an equity product?
The answer matters because the CAPE ratio is not obscure. It is one of the most useful long-term valuation tools investors have. It is also uncomfortable when markets are expensive.
Chapter 1: What the CAPE ratio is
The Cyclically Adjusted Price-to-Earnings ratio, often called the Shiller P/E or CAPE, was developed by economist Robert Shiller and John Campbell. Instead of dividing price by one year of earnings, it compares the market price with the average of the previous ten years of inflation-adjusted earnings.
That adjustment is powerful. One year of earnings can be distorted by recessions, booms, write-downs or temporary margins. Ten years smooth the cycle and give investors a clearer view of how much they are paying for normalized profits.
Why ten years?
A decade usually covers a full economic cycle: expansion, stress, recovery and renewed growth. CAPE is not designed to predict next month. It is designed to frame the next decade.
Chapter 2: The table investors should know
Historically, starting valuation has been strongly related to subsequent long-term real returns. The relationship is not perfect, but the direction is hard to ignore:
| Starting CAPE | Average real annual return over the following 10 years |
|---|---|
| < 10 | ~9-10% |
| 10-15 | ~7-9% |
| 15-20 | ~6-8% |
| 20-25 | ~4-6% |
| 25-30 | ~2-4% |
| 30-40 | ~0-3% |
| > 40 | near zero or negative |
When CAPE moves above 40, investors are no longer buying a normal market at a normal price. They are buying a very optimistic future.
Chapter 3: Selective memory in finance
In early 2009, when markets were cheap, long-term valuation arguments were everywhere. CAPE helped justify buying equities after a brutal crash. That was useful for investors, but it was also commercially convenient for the financial industry.
When valuations are high, the language often changes. CAPE gives way to forward P/E, recent averages, sector narratives, productivity stories and the familiar claim that the old rules no longer apply.
This is not always malicious. It is often simpler than that: financial institutions have incentives, and incentives shape communication.
Chapter 4: The costliest phrase in investing
"The four most expensive words in investing are: this time is different." - Sir John Templeton
Every expensive market has a story. In 1929 it was a new industrial age. In 1999 it was the internet. In 2007 housing could supposedly never fall nationwide. In 2021 low rates and speculative assets were presented as a new reality.
| Period | The story | What followed |
|---|---|---|
| 1929 | Technology had changed the economy | Deep market crash |
| 1999 | The internet changed valuation rules | Dot-com collapse and a lost decade |
| 2007 | Housing was structurally safe | Global financial crisis |
| 2021 | Zero rates justified everything | Major drawdowns in risk assets |
| 2026 | Artificial intelligence changes everything | Time will tell |
Innovation can be real and prices can still be excessive. Both things can be true at the same time.
Chapter 5: The incentive problem nobody likes to discuss
Banks and product distributors generally earn more when clients invest more assets through them. That does not make every recommendation wrong, but it changes the frame.
- Assets under management generate recurring fees.
- Financial products often carry margins, rebates or distribution incentives.
- Advisers and sales networks may be rewarded for flows and retention.
- Institutional businesses benefit from active capital markets.
If a valuation metric encourages clients to invest, it is easy to promote. If the same metric suggests caution, it becomes commercially inconvenient.
Before accepting a market narrative, ask: who benefits if I believe this?
Chapter 6: Diversification through a valuation lens
CAPE also helps investors think globally. Not every market trades at the same valuation. A portfolio heavily concentrated in expensive US mega-cap equities may carry a different long-term return profile than a more geographically diversified allocation.
| Market | Indicative CAPE context |
|---|---|
| United States | historically expensive |
| Europe | materially lower |
| Japan | lower than the US |
| Emerging markets | often lower, with higher country risk |
Valuation is not a timing signal, but it is a useful compass. It can help investors avoid assuming that yesterday's winning region must automatically dominate tomorrow.
Chapter 7: What to do with this information
This is not a call to sell everything. CAPE does not forecast crashes, and expensive markets can become even more expensive. But it should influence five practical decisions:
- Asset allocation: understand how much of your portfolio depends on one expensive market.
- Return expectations: avoid building plans on historical averages that ignore starting valuation.
- Time horizon: money needed in five to seven years should not rely blindly on equity optimism.
- Instrument selection: compare global, value, equal-weight and regionally diversified exposures.
- Adviser conversations: ask which valuation metrics are being used, and why.
Conclusion: the final question
Markets cannot be predicted in the short run. But long-term expected returns are not magic. Starting valuation matters. CAPE is not perfect, but it forces investors to confront the price they are paying.
The real problem is not that the information is unavailable. The problem is that some information is less profitable to discuss.
The next time someone offers you a free financial recommendation, ask what they are being paid to ignore.
Educational content only. This article is not investment, tax or legal advice.