Two investments, one number apart: a 10-year Treasury bond and the S&P 500 both promise a return. The gap between them, priced by the entire market every single day, is called the equity risk premium — and right now it is sitting at a level that explains most of what has happened to stock valuations over the last three years.
What the Equity Risk Premium Actually Measures
The equity risk premium (ERP) is the extra return stocks are expected to deliver over a risk-free benchmark — almost always the 10-year US Treasury yield — to compensate investors for the added uncertainty of owning a business instead of lending money to the government. A Treasury bond has a contractually fixed payment and is backed by the full faith and credit of the US government. A share of stock has no such guarantee: earnings can miss, competitors can appear, a recession can cut a dividend to zero. The ERP is the market's collective price for that difference.
The relationship is a single line:
Required Equity Return = Risk-Free Rate + Equity Risk Premium
Rearranged, that means the ERP itself is simply:
Equity Risk Premium = Required (or Expected) Equity Return − Risk-Free Rate
Everything that matters about the ERP follows from that one identity. If the risk-free rate rises and the ERP investors demand stays constant, the required return on stocks rises too — and since a stock's price is the present value of its future cash flows discounted at that required return, a higher required return mechanically produces a lower justified price for the same stream of earnings. This is the single biggest reason interest rate moves affect stock valuations even when nothing about the underlying businesses has changed at all.
Two Ways to Calculate It: Historical vs. Implied
There are two fundamentally different ways analysts estimate the ERP, and they answer different questions.
The historical (realized) ERP looks backward. It takes the actual average return stocks delivered over some long stretch of history — commonly since 1926 or 1928, when reliable US market return data begins — and subtracts the average return on Treasuries over that same period. This approach answers: "What premium has the stock market actually paid out, on average, over the long run?" Depending on the exact window, the choice of arithmetic vs. geometric averaging, and whether Treasury bills or Treasury bonds are used as the risk-free proxy, published estimates for the long-run US historical ERP typically fall somewhere in a 4% to 6% range, with some methodologies producing figures outside that band.
The implied (forward-looking) ERP looks forward instead. It starts from today's stock market price and today's consensus earnings estimates, solves backward for the discount rate that makes the math work, and subtracts the current risk-free rate from that discount rate. This approach answers a different question: "Given what stocks cost right now, and what they are expected to earn, what premium is the market actually pricing in today?" This number moves constantly, because it reacts to two things that change every day — stock prices and interest rates — rather than to decades of settled history.
| Approach | What It Measures | Typical Long-Run Range | What Moves It |
|---|---|---|---|
| Historical (realized) ERP | Average premium stocks actually delivered over decades | Roughly 4% to 6% | Only changes slowly, as history accumulates |
| Implied (forward-looking) ERP | Premium priced into today's market given current earnings and prices | Has ranged from roughly 2% to over 7% | Stock prices, interest rates, and earnings estimates — daily |
The implied ERP is the more useful number for a present-day decision, because it reflects current conditions rather than a decades-long average that includes market environments nothing like today's. NYU professor Aswath Damodaran, whose monthly implied ERP series is one of the most widely cited in the industry, has documented the swings directly: the implied US ERP compressed to close to 2% at the peak of the late-1990s dot-com bubble, when stock prices had detached from earnings, and spiked above 6% to 7% during the 2008 financial crisis, when stocks became historically cheap relative to what they were earning.
Where the ERP Stands Right Now
As of the most recent trading data, the 10-year US Treasury yield sits at 4.64%, and current market-based estimates of the US equity risk premium put it at roughly 4.5%. Add those together, and the market's implied required return on US equities works out to approximately 9% in nominal terms — a useful anchor for judging whether a given expected return on a stock or portfolio is actually compensating for the risk being taken, or falling short of it.
| Component | Current Level |
|---|---|
| 10-year US Treasury yield | ~4.64% |
| Estimated US equity risk premium | ~4.5% |
| Implied required return on equities | ~9% (nominal) |
That combination matters because it did not always look like this. The 10-year Treasury yield spent most of the 2010s and the pandemic years below 2%, and briefly traded near 1.5% in early 2022. As the Federal Reserve moved its policy rate from near zero to above 5% between 2022 and 2023 to fight inflation, the 10-year yield rose sharply, eventually approaching 5% by late 2023. That shift alone raised the risk-free half of the equation by roughly three percentage points in under two years — and unless the equity risk premium investors demanded fell by a matching amount, the required return on stocks had to rise with it, which is a large part of why 2022 was a difficult year for equity valuations even in sectors where underlying earnings held up fine.
The Fed Model: A Simpler, Cruder Version of the Same Idea
A more informal version of this comparison, popularized in market commentary in the late 1990s and often called the Fed Model, compares the S&P 500's earnings yield — earnings divided by price, the mathematical inverse of the P/E ratio — directly against the 10-year Treasury yield.
| S&P 500 Metric | What It Represents |
|---|---|
| Earnings Yield (E/P) | What $1 invested in the index "earns" per year, in current-earnings terms |
| 10-Year Treasury Yield | What $1 invested in a risk-free bond yields per year |
| Gap Between Them | The rough, unadjusted stock-vs-bond attractiveness spread the Fed Model watches |
When the earnings yield sits meaningfully above the Treasury yield, the Fed Model reads that as stocks looking cheap relative to bonds. When the gap narrows or inverts — as it has at various points when Treasury yields climbed sharply — the model reads that as stocks looking expensive relative to the safe alternative.
The Fed Model was never an actual Federal Reserve policy tool; it earned its name from a mid-1990s Fed report that simply noted the historical relationship, and traders adopted the label. It also has a real conceptual flaw worth understanding rather than ignoring: bond coupons do not grow, but company earnings generally do over time, so a stock market that permanently trades at a somewhat lower earnings yield than bonds is not automatically irrational — it can be paying for growth the bond will never deliver. Most professional investors treat the Fed Model, and the ERP more broadly, as one directional input to weigh alongside earnings growth expectations, credit conditions, and sector positioning — not as a standalone signal to buy or sell.
Why the ERP Compresses and Expands
The ERP is not a fixed number the market is trying to return to. It moves for identifiable reasons, and knowing which direction it is moving — and why — is more useful than memorizing a single "normal" figure.
What compresses the ERP (stocks get relatively less compensated for risk):
- Rapidly rising interest rates that outpace any offsetting rise in the equity risk premium, as happened through 2022
- Periods of strong investor optimism and low perceived risk, which push stock prices up faster than earnings, mechanically lowering the earnings yield
- Extended bull markets, where confidence about future earnings growth reduces the premium investors feel they need for uncertainty
What expands the ERP (stocks offer relatively more compensation for risk):
- Sharp equity selloffs and crises — 2008, and the initial 2020 pandemic crash — when investors flee to the safety of Treasuries, pushing bond prices up and yields down, while simultaneously demanding a much larger premium to hold stocks at all
- Elevated macro uncertainty (geopolitical shocks, recession fears, credit stress) that raises the perceived risk of equity ownership independent of what any single company is doing
- Periods when earnings estimates fall faster than stock prices have already adjusted, temporarily pushing the earnings yield up
The pattern worth internalizing is that ERP expansion tends to happen exactly when it feels least comfortable to be adding equity exposure, and ERP compression tends to happen exactly when it feels most comfortable. That is not a coincidence — it is the same investor psychology that drives the premium in the first place, just described from the other side.
What This Means for Position Sizing and Sector Allocation
The ERP is more useful as a risk gauge than as a market-timing signal, but it has real, practical implications for how a portfolio is built at any given moment.
When the implied ERP is compressed (stocks are being priced with little extra compensation for risk relative to bonds), the valuation cushion for being wrong on any individual position is thin. This is generally the environment where being more selective pays off: favoring businesses with durable cash flows and reasonable multiples over speculative, long-duration growth stories whose valuations depend most heavily on the exact discount rate used, since those are the names most sensitive to any further rise in rates or premium.
When the implied ERP is elevated (typically following a sharp selloff), the market is pricing in an unusually large amount of compensation for equity risk relative to the safe alternative. Historically, starting points with an elevated ERP have tended to be followed by above-average forward equity returns, which is the standard argument for treating a genuine risk-off spike as an opportunity to add exposure rather than a signal to retreat further — though this is a probabilistic tendency across history, not a guarantee for any single instance.
Rate-sensitive sectors deserve particular attention in either direction. Long-duration growth stocks, high-multiple technology names, and non-dividend-paying businesses whose value is weighted toward earnings many years out are the most mathematically exposed to ERP and rate swings, because more of their valuation depends on cash flows far in the future that get discounted more heavily when rates rise. Utilities, REITs, and other bond-proxy sectors move for a related but distinct reason: they compete directly with Treasuries for income-seeking capital, so their yields tend to track the risk-free rate closely.
Common Mistakes Investors Make With the ERP
- Treating the historical average as a fixed target the market must return to. The 4% to 6% long-run figure is an average across a century of very different market regimes, not a magnetic level the implied ERP snaps back to on any predictable schedule.
- Ignoring which risk-free rate is being used. Comparing today's implied ERP to an older estimate calculated against a different point on the yield curve, or against Treasury bills instead of the 10-year note, produces an apples-to-oranges comparison.
- Using the Fed Model as a precise valuation tool rather than a directional gut-check. It ignores earnings growth entirely, which is a real analytical gap, not a minor simplification.
- Assuming a low ERP means an imminent crash. A compressed premium is a signal that less margin for error exists, not a timing mechanism — compressed premiums can persist for years before any correction arrives.
- Applying one market-wide ERP uniformly across every stock. The market-wide ERP is an average; individual companies carry their own risk characteristics (leverage, earnings volatility, competitive position) that justify a company-specific premium above or below the index-wide figure.
Track It Live
The equity risk premium moves with two things that change constantly: interest rates and stock prices. Watch the 10-year Treasury and broad market levels alongside individual holdings with Stock Alarm Pro's live market explorer, free with no signup required, or run a valuation-focused screen for reasonably priced, cash-generative businesses with the stock screener. For rate-sensitive positions already in a portfolio, a price or fundamentals alert can flag a meaningful move without requiring a daily check on where yields are heading.
This article is for educational purposes only and does not constitute investment advice. Historical and implied equity risk premium figures cited above are approximate, vary by data source and methodology, and change continuously with market conditions. Past performance is not indicative of future results. Always do your own research and consult a licensed financial advisor before making investment decisions.
