What is the Cyclically Adjusted Price-to-Earnings (CAPE) Ratio?

The Cyclically Adjusted Price-to-Earnings (CAPE) Ratio, also known as the Shiller P/E Ratio, is a financial metric used to assess whether a stock or market is overvalued, undervalued, or fairly valued by comparing current stock prices to inflation-adjusted earnings over a longer time horizon. It was popularized by economist Robert Shiller and has become a widely recognized tool for long-term market evaluation.

Origins of the CAPE Ratio

The CAPE ratio was developed by Yale University economist Robert Shiller and his colleague John Campbell in the late 1980s and gained wider recognition after the dot-com bubble of the early 2000s. Shiller created the CAPE ratio as an improvement upon the traditional Price-to-Earnings (P/E) ratio, which often failed to account for the cyclical nature of corporate profits. Shiller's version adjusts for economic cycles by taking into account earnings over a period of ten years, rather than focusing on a single year's earnings as is done with the standard P/E ratio.

The rationale behind the CAPE ratio is that corporate profits and stock prices are influenced by economic cycles. As a result, profits may fluctuate significantly during economic booms and busts, which can distort the traditional P/E ratio. By averaging earnings over a longer period and adjusting for inflation, the CAPE ratio provides a more stable and long-term view of valuation.

Calculation of the CAPE Ratio

To calculate the CAPE ratio, the following steps are involved:

1. Price Component: The numerator of the CAPE ratio is the current price of the stock or market index (e.g., the S&P 500).
2. Earnings Component: The denominator is the average of inflation-adjusted earnings over the last ten years. This smoothing process eliminates short-term fluctuations in earnings that might result from temporary economic conditions.
3. Adjusting for Inflation: To account for the impact of inflation on earnings, the earnings from each of the past ten years are adjusted using the Consumer Price Index (CPI) or another measure of inflation. This ensures that both the price and earnings are in "real" terms, meaning adjusted for inflation.

The formula for the CAPE ratio is as follows:

\text{CAPE} = \frac{\text{Current Price}}{\text{Average Inflation-Adjusted Earnings Over 10 Years}}

By smoothing earnings over a decade, the CAPE ratio attempts to reduce the volatility that can arise from short-term market conditions, which are often reflected in year-to-year earnings.

Interpretation of the CAPE Ratio

The CAPE ratio is primarily used to assess the overall valuation of stock markets rather than individual stocks, although it can be applied to individual stocks as well. It is particularly popular when evaluating the broader market indices, such as the S&P 500. The interpretation is straightforward:

• High CAPE Ratio: A higher-than-average CAPE ratio suggests that stocks are expensive relative to their historical earnings. This may indicate an overvalued market, implying the possibility of lower future returns as stock prices may not be supported by underlying earnings.
• Low CAPE Ratio: A lower-than-average CAPE ratio suggests that stocks are cheap relative to their historical earnings, indicating an undervalued market. This could imply higher future returns, as stock prices have room to grow if earnings recover or continue to increase.

The long-term average CAPE ratio for the S&P 500 has historically been around 16-17, but this average can fluctuate over time due to changes in economic conditions, earnings trends, and investor sentiment.

Strengths of the CAPE Ratio

1. Long-Term Perspective: One of the primary advantages of the CAPE ratio is its focus on long-term earnings, which helps to smooth out the volatility that can distort short-term valuation metrics. By averaging earnings over a ten-year period, the CAPE ratio provides a more stable and realistic assessment of market valuations.
2. Inflation Adjustment: By adjusting earnings for inflation, the CAPE ratio ensures that both the price and earnings components are measured in real terms. This makes the ratio more meaningful in periods of high inflation, when nominal earnings may be distorted by rising prices.
3. Cyclicality: Traditional valuation ratios can be misleading during certain phases of the business cycle. For example, during economic booms, earnings may be temporarily inflated, making stocks appear cheaper than they actually are. The CAPE ratio helps to mitigate this problem by smoothing earnings over a full economic cycle.
4. Predictive Power: Historically, the CAPE ratio has shown some ability to predict long-term stock market returns. High CAPE ratios have often preceded periods of lower returns, while low CAPE ratios have often been followed by periods of higher returns.

Limitations of the CAPE Ratio

1. Not for Short-Term Predictions: While the CAPE ratio has demonstrated some success in predicting long-term market returns, it is not a reliable tool for short-term market timing. Markets can remain overvalued or undervalued for extended periods, and the CAPE ratio may not provide much insight into short-term movements.
2. Sector and Structural Changes: The CAPE ratio may not fully account for significant structural changes in the economy or financial markets. For instance, changes in tax policies, shifts in industries, or the rise of new sectors (e.g., technology) may lead to permanently higher or lower earnings levels compared to the past. In such cases, a high CAPE ratio may not necessarily signal overvaluation.
3. Earnings Volatility: While smoothing earnings over ten years helps reduce volatility, the CAPE ratio can still be affected by extreme earnings events in the distant past, such as financial crises or recessions. In these cases, the ten-year average may not fully reflect current earnings power.
4. Interest Rates and Risk Premiums: The CAPE ratio does not directly take into account interest rates or the equity risk premium, both of which can influence stock valuations. For example, when interest rates are low, investors may be willing to pay higher prices for stocks, leading to higher CAPE ratios without necessarily signaling a bubble.

Comparison to Other Valuation Metrics

The CAPE ratio is one of many tools available to investors for assessing market valuations. It is often compared to other valuation metrics, including:

• Price-to-Earnings (P/E) Ratio: The P/E ratio is the most commonly used valuation metric and compares current stock prices to the most recent year's earnings. Unlike the CAPE ratio, it does not smooth earnings over time, making it more volatile and susceptible to short-term fluctuations.
• Price-to-Book (P/B) Ratio: The P/B ratio compares stock prices to a company's book value, or the value of its assets minus liabilities. While useful for certain sectors (e.g., financials), it may be less relevant for companies with large intangible assets (e.g., technology firms).
• Dividend Yield: The dividend yield measures the annual dividend payments relative to stock prices. While a useful measure for income-oriented investors, it may not fully capture growth potential, especially for companies that do not pay dividends.
• Enterprise Value-to-EBITDA (EV/EBITDA): This ratio is commonly used for valuing companies based on their operating earnings (EBITDA) relative to their enterprise value. It is often used in merger and acquisition analysis but focuses on a company’s core operations rather than its earnings over time.

Each of these metrics has its own strengths and weaknesses, and the CAPE ratio is best used in conjunction with other valuation tools.

Real-World Examples of CAPE Ratio Usage

1. Dot-Com Bubble (Late 1990s): The CAPE ratio for the S&P 500 soared to unprecedented levels during the late 1990s, reaching nearly 44 at the height of the dot-com bubble. This indicated extreme overvaluation relative to historical earnings, and the bubble eventually burst in 2000, leading to a sharp market decline over the next few years.
2. Global Financial Crisis (2007-2009): In the lead-up to the 2008 financial crisis, the CAPE ratio was elevated but not at extreme levels. However, following the market crash, the ratio dropped to a low of around 13, suggesting undervaluation. Investors who bought into the market during this period saw strong long-term returns as the market recovered in subsequent years.
3. Post-COVID Recovery (2020-2021): After the market crash in early 2020 due to the COVID-19 pandemic, the CAPE ratio quickly rebounded and reached historically high levels by 2021, fueled by low interest rates, fiscal stimulus, and investor optimism. Some analysts raised concerns about overvaluation, though the market continued to rise for some time.

The Bottom Line

The CAPE ratio is a valuable tool for long-term investors looking to assess market valuations, particularly when considering broader market indices like the S&P 500. By smoothing earnings over a ten-year period and adjusting for inflation, the CAPE ratio provides a more stable view of valuations compared to the traditional P/E ratio. However, like any metric, it has limitations and should be used in conjunction with other indicators to form a comprehensive view of the market. While it has shown some predictive power over long-term returns, it is not a reliable tool for short-term market timing.