The Equity Risk Premium: Expected Returns vs Risk-Free Rate

The equity risk premium is the only number that matters in finance, and most investors can't define it.

Here's what you need to understand: the equity risk premium is the additional return investors demand for holding stocks instead of risk-free assets. That's it. Stocks are risky. Treasury bills aren't. The premium is what you get paid for taking that risk. But like everything in finance that sounds straightforward, the moment you try to pin it down precisely, it becomes wonderfully complicated.

Start with the building blocks. The risk-free rate is what you earn on an asset with zero default risk and zero volatility. In the United States, that's the three-month Treasury bill or the ten-year Treasury note, depending on your time horizon. Right now, as I'm speaking, the ten-year is yielding around four and a quarter percent. That's your baseline. That's what you get for doing absolutely nothing except lending money to the most creditworthy borrower on earth.

Now stocks. The expected return on stocks is what you think the market will deliver going forward. Notice I said expected, not historical. This is where people trip up immediately. They look at the past hundred years and say stocks returned ten percent annually, so the equity risk premium must be ten minus whatever risk-free rate we're using. Wrong. That's the realized premium, not the expected premium. What happened is not what people thought would happen. The premium you demand today reflects your beliefs about tomorrow, not a summary of yesterday.

The equity risk premium is expected stock returns minus the risk-free rate. If you expect stocks to return eight percent and the ten-year Treasury yields four percent, your equity risk premium is four percent. That four percent is your compensation for the uncertainty, the volatility, the fact that stocks can cut in half while your Treasury just sits there accruing interest.

Here's where it gets interesting. This premium is not constant. It moves. It breathes. It changes with market cycles, with economic conditions, with sentiment and fear and greed. In two thousand and nine, after Lehman Brothers collapsed and the S&P was trading at a Shiller PE of thirteen, the equity risk premium was massive. Investors were terrified. They demanded enormous compensation to own stocks. You could buy equity cash flows at valuations that implied double-digit returns against a risk-free rate near zero. That's a premium of ten percent or more. Stocks were cheap because fear was expensive.

Fast forward to late twenty twenty-one. The S&P hit a Shiller PE over thirty-eight. The risk-free rate was still low, maybe one and a half percent on the ten-year. But now implied future stock returns were maybe six or seven percent at best. The equity risk premium had compressed to four or five percent. Investors weren't scared. They were buying. They didn't demand much compensation for risk because they didn't believe there was much risk.

This is the cycle. When stocks are cheap, the premium is high. When stocks are expensive, the premium is low. The premium reflects collective sentiment about uncertainty. And uncertainty is expensive when people remember pain and cheap when they forget it.

Now let's talk about why this matters for valuation. Every single model for pricing stocks uses the equity risk premium. The dividend discount model, the discounted cash flow model, the capital asset pricing model—all of them require you to estimate expected returns. And expected returns are built from the risk-free rate plus the equity risk premium.

Take a discounted cash flow model. You're valuing a company by estimating its future cash flows and discounting them back to today. The discount rate you use is the required return. For equity, that's the risk-free rate plus the equity risk premium, adjusted for the specific risk of that company through beta. If you assume a five percent premium and the real premium investors demand is seven percent, you're going to overpay. Your model says buy. The market says you're wrong.

This is not theoretical. In the late nineties, analysts were using equity risk premiums of three percent, maybe less. They justified nosebleed valuations on tech stocks because their models said those stocks were fairly priced. The problem wasn't the math. The problem was the assumption. They assumed investors would accept tiny premiums forever. They didn't. When sentiment shifted, the premium expanded, required returns rose, and valuations collapsed. Garbage in, garbage out.

So how do you estimate the equity risk premium? There are two main approaches. The first is historical. You look at long-term stock returns, subtract long-term bond returns, and call that your premium. Dimson, Marsh, and Staunton have done this across multiple countries over more than a century. For the U.S., the historical premium is somewhere between four and six percent, depending on whether you use arithmetic or geometric means and which risk-free rate you pick.

The problem with the historical approach is that it assumes the future will look like the past. Maybe it will. Maybe it won't. If structural changes occur—lower growth, higher taxes, different monetary policy—the old premium might not apply.

The second approach is forward-looking. You reverse-engineer the premium from current market prices. You take the current level of the S&P, estimate future earnings or dividends, and solve for the discount rate that makes the present value equal the current price. That discount rate is the expected return. Subtract the risk-free rate, and you have the implied equity risk premium.

Aswath Damodaran at NYU does this every month. He publishes the implied premium for the S&P. As of the latest update, it's hovering in the low to mid-four percent range. That's below the long-term historical average. What does that tell you? It tells you that either investors are optimistic about future growth, or they're not demanding much compensation for risk, or both. It tells you stocks aren't screaming cheap.

Here's the practical takeaway for you as an investor. When someone tells you a stock is undervalued, ask what equity risk premium they're using. If they say three percent and you believe the market demands six percent, their valuation is fantasy. The premium assumption drives everything. Change it by one percentage point, and fair value can shift by twenty or thirty percent.

Also, understand that the premium is mean-reverting over the long term, but it can stay extreme for years. You can't time it precisely. But you can recognize when it's compressed to dangerous levels. When everyone is comfortable, when volatility is low, when stocks are priced for perfection, the premium is probably too low. That's not a market to be aggressive in.

Conversely, when fear is pervasive, when stocks have been cut in half, when the news is apocalyptic, the premium is probably elevated. That's when you get paid to take risk. That's when future returns are built.

The equity risk premium is the engine of every valuation model. It's the knob that turns investor psychology into numbers. It's the reason stocks are higher-returning than bonds over time, and it's the reason stocks can destroy you in the short run. Ignore it, and you're guessing. Respect it, and you have a framework.

See you Monday.

The premium you demand reveals what you believe about the future, and what you believe determines what you pay.