The equity risk premium is the additional return that investing in the stock market provides over a risk-free rate, compensating investors for taking on the higher risk of equity investments.
The risk-free rate is typically the 10-year U.S. Treasury yield. Historical ERP for U.S. stocks has averaged 4–6% over the past 100 years. For individual stocks, use CAPM: Expected Return = Risk-Free Rate + Beta × ERP.
If the S&P 500 is expected to return 10% and the 10-year Treasury yields 4%, the equity risk premium is 6%. For a stock with a beta of 1.3, the expected return = 4% + 1.3 × 6% = 11.8%. This means investors demand 11.8% from this stock to compensate for its risk level. A defensive utility stock with beta 0.6 would have an expected return of 4% + 0.6 × 6% = 7.6%.
A higher equity risk premium means stocks are expected to outperform bonds by a wider margin — typically occurring during market downturns when stock prices are depressed and future returns look attractive. A low or shrinking ERP suggests stocks may be expensive relative to bonds, signaling caution. Historically, ERP has ranged from 2% (during bubbles) to 8%+ (during crises). The current ERP helps investors decide their stock/bond allocation.
The equity risk premium is the cornerstone of modern finance. It underpins the Capital Asset Pricing Model (CAPM), which is used to calculate the cost of equity for every publicly traded company. When a CFO decides whether to invest in a new factory, when an investment banker values a company for an IPO, or when a portfolio manager allocates between stocks and bonds, they all rely on estimates of the equity risk premium. It is arguably the single most important number in finance.
For individual investors, ERP provides a framework for asset allocation decisions. When the ERP is historically high (above 6%), it favors increasing equity exposure. When it's low (below 3%), it favors bonds, cash, or alternative investments. During the dot-com bubble of 1999, the ERP dropped to near zero as stock valuations reached extreme levels — a clear warning signal for investors who were paying attention. Conversely, in March 2009, the ERP soared as stock prices collapsed, signaling one of the best buying opportunities in decades.
The debate over the "correct" ERP is one of finance's most contentious topics. Historically, U.S. stocks have delivered a real (inflation-adjusted) return of about 7% versus 2–3% for bonds — a 4–5% ERP. However, some academics argue the forward-looking ERP is lower (3–4%) due to lower transaction costs, better diversification options, and increased global equity demand. Whatever estimate you use, consistency matters more than precision — use the same ERP assumption throughout your analysis.
In March 2009, the S&P 500 had fallen to 666 from its 2007 high of 1,565. The earnings yield on the S&P 500 (inverse of PE ratio) was approximately 10%, while 10-year Treasury yields were about 3%. The implied ERP was roughly 7% — well above the historical average. Investors who recognized this elevated risk premium and increased equity exposure earned extraordinary returns as the S&P 500 tripled over the following five years. The high ERP was the market's way of compensating investors willing to bear risk during maximum fear.
Conversely, in early 2000, the S&P 500's earnings yield was approximately 3% (PE of 33) while Treasury yields were 6.5%. The ERP was negative — stocks were expected to return less than risk-free bonds. This was a powerful signal that equities were dramatically overvalued, and indeed the S&P 500 lost nearly 50% over the following two years.
Calculate implied ERP from market data: Take the S&P 500 earnings yield (1/PE) and subtract the 10-year Treasury yield. This gives a real-time market-implied ERP. If it's above 5%, equities are attractive; below 2%, be cautious.
Use ERP to set your equity allocation: When ERP is high (5%+), tilt toward equities. When low (below 3%), increase bonds and cash. This dynamic allocation strategy has historically outperformed fixed allocations.
Calculate expected returns using ERP:
Try Valuation Calculator →What is a risk premium?
The extra return investors demand for taking on risk instead of holding risk-free assets (like Treasury bills). The equity risk premium — stocks' excess return over Treasury bills — has historically been 4-6% annually. If T-bills yield 5% and stocks return 10%, the risk premium is 5%. Higher risk requires higher expected returns.
What is the equity risk premium today?
Estimates vary. Using the Shiller CAPE ratio, the forward equity risk premium is currently below historical averages (2-4% vs. the typical 4-6%). This means stocks are priced for lower future excess returns. When the risk premium is low, diversifying into other assets (bonds, real estate, international stocks) becomes more important.
Does risk premium guarantee higher returns?
No — it's an expected return, not guaranteed. Over short periods (even 10 years), stocks can underperform bonds. The risk premium is realized over very long periods (20-30+ years). This is why your time horizon matters: if you need money in 3 years, the equity risk premium may not help you.