The Conference Board Leading Economic Index lands at 10:00 ET on the third Thursday of most months, and every desk reads two numbers off it: the month-over-month percent change on the headline, and the six-month diffusion index across the ten components. The headline moves markets in single-decimal increments. The diffusion index moves the recession call. The 47 line on the diffusion index is the level the Conference Board publishes as the historical recession-signal threshold, and it is the number that carries the interpretive weight.

What the LEI actually is

The Leading Economic Index is a composite of ten forward-looking series weighted to produce a single index level normalized to 100 in 2016. The ten components: average weekly hours in manufacturing, average weekly initial claims for unemployment insurance, manufacturers’ new orders for consumer goods and materials, the ISM new orders diffusion index, manufacturers’ new orders for nondefense capital goods excluding aircraft, building permits for new private housing, S&P 500 stock prices, the Leading Credit Index (a Conference Board proprietary series), the ten-year Treasury minus fed funds spread, and average consumer expectations for business conditions.

The construction weights the components inversely to the standard deviation of their month-over-month changes, so no single high-volatility series dominates. Building permits and the yield-curve spread carry the largest structural weights in the current vintage. The stock-price contribution carries the largest month-to-month volatility.

The diffusion index math

Alongside the headline percent change, the Conference Board publishes a six-month diffusion index measuring the fraction of the ten components moving in the same direction across a six-month rolling window. A component gets plus one if it rose over the six-month window, zero if unchanged, and minus one if it fell. The diffusion index is the average across the ten components, rescaled to the zero-to-100 range where 50 means the components are evenly split.

A diffusion reading of 60 means six of ten components rose over the trailing six months. A reading of 40 means only four of ten rose. The reading captures breadth of the underlying signal, which the headline percent change does not: a headline driven by a single large positive contribution (a stock-price surge, for instance) reads as strong on the percent change but weak on the diffusion index.

The 47 line

The Conference Board publishes the six-month diffusion reading of 47 as the historical recession-signal threshold. Across the eight recessions since 1960 in the LEI reference sample, the diffusion index has crossed under 50 an average of six to eight months before the NBER-dated recession start, and it has crossed under 47 an average of four to six months before the start. The signal is not deterministic. The diffusion index has printed under 50 four times since 1960 without a recession following inside the twelve-month window, most recently across late 2015 and mid-2016 during the industrial-and-energy slowdown that did not become a broad recession.

The threshold behavior is why the Conference Board publishes both the headline and the diffusion side by side in its monthly release, and why the interpretive language in the release itself keys off the diffusion print rather than the percent change.

What the current print reads

The May 2026 LEI diffusion index at 48 sits one point above the 47 signal line. The May headline at minus 0.1 percent month-over-month carried the six-month annualized rate at minus 2.8 percent, compressed from the minus 3.1 percent April read. The combination reads as breadth deterioration compressing and magnitude softening: the diffusion is still under 50 (bearish), but the six-month rate is closing the gap to zero (less bearish).

The June print landing today at 10:00 ET is the first data point in a three-month window where the diffusion index has a live path to cross either above 50 (retracing the 2025 through early 2026 signal) or below 47 (confirming a recession call the strip is not yet pricing). The six-month annualized rate at minus 2.5 percent or narrower confirms the compression. A widening to minus 3.0 percent or wider breaks the compression and lifts the probability that the diffusion crosses 47 by the September print.

What the LEI does not do

The LEI does not forecast the timing of a recession. It signals the direction of the aggregate leading-indicator picture. The Conference Board is explicit that a diffusion reading under 47 combined with a headline six-month annualized rate under minus 4.2 percent is the joint threshold that has produced the cleanest historical recession signal. The May reading at 48 and minus 2.8 clears one threshold and fails the other. The June print is what tightens or loosens that joint condition.

The LEI is also not the number the FOMC prices its own recession probability from. The Committee reads the SEP unemployment rate projection, the Fed staff Tealbook probability distribution, and the regional Fed indexes in aggregate. The LEI is a private-sector composite that market desks watch as one input into the recession call, and its diffusion index is the single most-watched summary number inside that composite.

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