Equity Risk Premium

The excess return that investing in the stock market provides over a risk-free rate, compensating investors for taking on higher volatility.

The equity risk premium (ERP) is the excess return that investors expect to receive for holding equities over a risk-free asset, such as long-term government bonds. Because stocks carry higher volatility, liquidity risk, and default risk than government debt, investors demand a premium to incentivize them to allocate capital to the stock market. The ERP is a foundational concept in financial theory, serving as a key input for calculating the cost of equity and valuing businesses. To observe or estimate the equity risk premium, analysts generally look at either historical data or implied forward-looking data. The historical approach calculates the actual difference between stock market returns and government bond yields over several decades. The forward-looking approach estimates future stock market returns—often using current valuation metrics like the earnings yield—and subtracts the current yield of a benchmark government bond, such as the 10-year Treasury. Investors care about the equity risk premium because it helps guide asset allocation decisions. A high ERP suggests that stocks are undervalued or highly attractive relative to bonds, offering strong potential compensation for taking on equity market volatility. Conversely, a low or compressed ERP indicates that stocks are expensive and that investors are not being adequately compensated for taking on stock market risk compared to the guaranteed yields of risk-free debt, which may prompt a shift toward safer assets.

If the expected annual return of the S&P 500 is estimated at 8.5% based on current earnings yields, and the yield on a risk-free 10-year Treasury bond is 4.0%, the equity risk premium is 8.5% - 4.0% = 4.5%.