What Is the Cyclically Adjusted Price-to-Earnings Ratio, or CAPE Ratio?

The cyclically adjusted price-to-earnings ratio is a variation of the classic price-to-earnings ratio that attempts to provide better long-term guidance on how a stock price compares to the underlying value of the company.

Keep reading to learn how to assess both individual stocks and entire foreign stock markets using the CAPE ratio.

Definition of the Cyclically Adjusted Price-to-Earnings Ratio

Invented by Nobel prize-winning economist Robert Shiller, the cyclically adjusted price-to-earnings ratio is a way of assessing how a stock's price compares to its company's value. Unlike the standard price-to-earnings ratio, the cyclically adjusted price-to-earnings ratio attempts to better account for long-term trends. This can make it a valuable tool for U.S. investors who are looking for opportunities abroad.

As with the standard P/E ratio, the higher the cyclically adjusted price-to-earnings ratio, the more overextended the stock price is believed to be. When the stock price runs too far ahead of the underlying value, investors could expect a pullback.

• Acronym: CAPE ratio
• Alternative name: Shiller P/E, P/E 10 ratio

How Do You Calculate the CAPE Ratio?

The CAPE ratio is calculated by dividing the current price of a single stock or a broad stock market index by the average inflation-adjusted earnings of the stock or the index components over the past 10 years. Instead of calculating each year's specific inflation level, some analysts apply a set inflation multiplier to each year’s EPS before dividing the total by 10 (to average out the decade's worth of EPS data).

How the CAPE Ratio Works

In general, the higher the CAPE ratio, the lower the expected annual returns in the coming years. This assessment works for domestic stock indexes like the S&P 500, but the same metric can also be applied to frontier and emerging equity indexes to determine their valuation, relative to historical norms. This helps to get a long-term view of a market that may be more subject to short-term volatility than an index like the S&P 500.

What It Means for Individual Investors

The CAPE ratio can be helpful for any investor—especially a value investor—who is looking for a way to assess stock prices and find undervalued investments. International investors may stand to gain the most from using the CAPE ratio, since the long-term view helps investors find good opportunities in volatile markets abroad.

International investors can quickly find CAPE ratios for various countries around the world using free online calculators, such as Barclay's Historic CAPE® Ratio by country interactive tool. Many online brokers also offer a suite of investment analysis tools that can provide the CAPE ratio for individual stocks, as well.

In general, a CAPE ratio of between 10 and 15 is considered ideal, while a ratio over 20 could indicate that the market is overvalued and could be due for a correction. It’s worth noting, however, that different markets have different absolute readings, so investors should also take a look at the bigger picture charts.

Many investors prefer to use the CAPE ratio to screen for countries or industries that are trading at a discounted valuation, and then they look for compelling individual opportunities within those countries using American Depositary Receipts (“ADRs”) or by purchasing foreign stocks directly.

Limitations of the CAPE Ratio

As with most financial ratios, investors should use the CAPE ratio in conjunction with other forms of analysis rather than relying on it exclusively. Knowing how a stock price compares to the underlying value is important, but it doesn't tell the whole story about the security or the broader market. A company's stock could be cheap, but if the broader market is in a downturn, the stock price could continue to fall regardless of whether it's cheap or expensive.

Another limitation is that the CAPE ratio requires at least 10 years of historical data, and not all countries have that kind of data readily available. It may be easy to find detailed financial information from companies in the U.S., the U.K., Canada, and Japan, but looking up market details may not be as easy when it comes to Austria, China, or Colombia, for example.

The Balance does not provide tax, investment, or financial services and advice. The information is presented without consideration of the investment objectives, risk tolerance, or financial circumstances of any specific investor and might not be suitable for all investors. Past performance is not indicative of future results. Investing involves risk, including the possible loss of principal.