Sahm Rule Recession Indicator

The Sahm Rule is a recession indicator built from a single ingredient: the unemployment rate. It signals that a recession has likely begun when the three-month moving average of the national unemployment rate rises by 0.50 percentage points or more above its lowest point in the prior twelve months. The value shown above is that gap, measured in percentage points — the distance between the recent smoothed unemployment rate and its rolling low. When it crosses 0.50, the rule has triggered.

What makes the Sahm Rule genuinely interesting is its origin and purpose. It was created by economist Claudia Sahm, who designed it not as an academic curiosity but as a real-time trigger — specifically, a fast, objective threshold that could automatically start sending stimulus payments to households the moment a downturn began, without waiting for officials to declare a recession after the fact. In other words it was engineered to fire early and mechanically, turning the well-known fact that unemployment rises quickly into a clean on-off signal.

Reading it is refreshingly simple. The closer the value is to zero, the further the labor market is from recession territory — the smoothed unemployment rate is near its own recent low. As the reading climbs toward 0.50, the labor market is loosening, and at 0.50 the rule is considered triggered. Because it is built on a three-month average rather than a single month, it filters out one-off noise while still reacting far faster than a formal recession call.

The elegance is that the rule captures velocity, not level. It does not care whether unemployment is 3.5% or 6%; it cares how far and how fast the rate has risen off its recent floor. This is why a labor market can have a historically low unemployment rate and still trip the Sahm Rule — what matters is the half-point rise from the trough, the signature of a labor market that has turned a corner.

Mechanically, the Sahm Rule is driven entirely by the unemployment rate, so everything that moves unemployment moves the rule. Layoffs, hiring freezes, and a softening of labor demand push the smoothed rate up off its low and lift the reading toward the threshold. A stable or falling unemployment rate keeps the reading pinned near zero, because the rolling twelve-month low keeps resetting alongside it.

There is a subtle wrinkle worth understanding. Because the rule compares against the lowest point of the prior twelve months, a rise can come either from genuine layoffs or, in unusual circumstances, from a surge in labor force participation that lifts the measured unemployment rate even as hiring stays solid. Sahm herself has noted that the rule is an empirical regularity, not a law of nature, and that a labor market reshaped by an unusual supply shock could in principle move the indicator for reasons that differ from a classic demand-driven recession.

Its track record is the reason it became famous. Applied historically, the Sahm Rule has identified every US recession since 1970 with no false positives — it triggered at or shortly after the onset of each downturn and stayed quiet in between. That combination of early timing and clean history is rare among recession indicators, most of which either fire late or cry wolf, and it is what earned the rule a place on the Federal Reserve's own data platform.

Then came its most debated moment. In mid-2024 the indicator crossed its 0.50 threshold, technically triggering even as the broader economy kept growing and the recession that the rule's history implied did not immediately materialize. Sahm herself publicly cautioned that the post-pandemic rise in unemployment was driven in part by a swelling labor force rather than a wave of layoffs, and that the rule might overstate the risk in such an unusual environment. The episode became a live case study in the limits of any single trigger — a reminder that an empirical rule built on past cycles can behave unexpectedly when the labor market is unusual.

The calculation takes the seasonally adjusted national unemployment rate, computes its three-month moving average, and subtracts the lowest value that three-month average reached over the previous twelve months. The result is the percentage-point gap shown above, and 0.50 is the trigger. The underlying unemployment data come from the Bureau of Labor Statistics; on FRED the real-time version is published as SAHMREALTIME, which uses the unemployment rate as it was actually reported at the time rather than later-revised figures.

That real-time distinction is the key methodological caveat. Because the unemployment rate gets revised and rebenchmarked, a version computed on final data can differ from what an observer would have seen live. The real-time series is designed to reflect what the rule would have signaled in the moment, which is the whole point of an indicator meant to trigger automatic policy. The trade-off is that early readings can shift slightly as the source unemployment data are revised.

The Sahm Rule is downstream of the Unemployment Rate by construction — it is that series transformed into a recession trigger, so the two should always be read together. The unemployment rate tells you the level and direction; the Sahm Rule tells you whether the rise off the trough has reached the historically significant half-point threshold. Initial Jobless Claims sit one step earlier in the chain, offering a weekly, leading read on layoffs that has historically begun rising before the Sahm Rule trips.

As a recession indicator, the Sahm Rule's natural cross-asset companion is the Yield Curve. The two are independent in their inputs — one is built from the labor market, the other from the bond market's expectations — so when an inverted curve and a triggered Sahm Rule agree, the recession signal has historically been more compelling than either alone. The broader growth charts here, US GDP, Industrial Production, and Retail Sales, then describe whether final demand is corroborating what the labor signal implies.

The macro-regime panel above places the current reading in context. The natural question is simply how close the value is to 0.50 and which direction it is moving — a reading hugging zero describes a labor market near its recent best, while a reading approaching or crossing the threshold has historically coincided with the early stages of a downturn. The 2024 episode is a standing reminder to read the trigger alongside its causes rather than treating the crossing as automatic.

This is context, not a forecast. The purpose of the regime overlay is to see whether the Sahm Rule agrees with the claims data, the yield curve, and the growth series, and to weigh whether any rise reflects classic layoff-driven weakening or an unusual labor-supply dynamic. A coherent signal across indicators has historically meant more than the rule read in isolation.

For long-term investors the Sahm Rule offers something rare: a single, objective, historically reliable marker of when a recession has likely begun, with a clean enough record to be worth respecting. Because recessions have historically coincided with weaker earnings and equity drawdowns, knowing that this trigger has fired — and reading it alongside its causes — helps frame whether the economic backdrop has shifted from expansion toward contraction.

The 2024 debate is the cautionary footnote. No single rule is infallible, and an indicator calibrated on past cycles can be wrong-footed by a genuinely unusual labor market, so the Sahm Rule is best used as one corroborating input rather than a standalone switch. Treat it as a well-built recession marker to weigh against the rest of the dashboard. This is a historical indicator, not investment advice.