What the 2s10s spread actually measures
The 2s10s spread is the simplest summary of the US Treasury yield curve: 10-year yield minus 2-year yield, expressed in percentage points. The Federal Reserve Bank of St. Louis publishes the series as T10Y2Y on FRED, derived from the underlying constant-maturity Treasury yields the US Treasury releases each day at the New York close.
A positive spread is the historical default. Long-dated bonds carry more duration risk so investors demand a higher yield to hold them — that's the term premium. In a normal expansion the spread sits between +100 and +250 basis points. Recessions tend to start with a steepening curve as the Fed cuts short rates, then end with the spread back at its long-run average.
Why inversion has preceded every US recession since 1955
The mechanism is straightforward. When the Fed hikes the federal funds rate aggressively to fight inflation, short-dated yields rise fast because the 2-year is closely anchored to fed funds expectations over the next two years. The 10-year rises too, but less, because traders are pricing in eventual rate cuts to deal with the slowdown the hiking cycle is causing. The math forces the curve to flatten and eventually invert. Inversion is the bond market's judgment that current policy is restrictive enough to bring growth (and inflation) down.
The track record is striking. Every US recession since 1955 (the start of the modern FRED data) was preceded by a 2s10s inversion. The lead time ranges from about 6 months to over 2 years — that range is what makes the signal famously useful as a directional warning but useless as a timing tool. See NBER's business cycle dating committee for the official US recession dates against which the signal is judged.
2s10s vs. 3m/10y — which curve does the Fed watch?
Fed economists prefer the 3-month / 10-year spread (T10Y3M) over the 2s10s. They argue the 3-month moves more closely with current monetary policy than market-priced 2-year expectations, giving a cleaner signal of when policy is actually restrictive. Wall Street still leads with 2s10s because it's where the duration-trade flows are. Empirically both inverted before each recent recession; 2s10s usually inverted first.
How inversion plugs into the rest of the macro picture
An inversion is one signal in a stack. It's most powerful when combined with sustained sub-trend GDP, rising unemployment, widening credit spreads, and a Fed policy stance that's already restrictive — see the fed funds cycle tracker for the current effective rate and cycle phase. Falling core PCE inflation into an inverted curve is the textbook setup for the Fed pivoting toward cuts, which historically precedes the recession itself by several months. None of this is investment advice.
Caveats
Twelve recessions is a small sample. Each inversion has its own context: the 1980 Volcker shock looked nothing like the 2007 housing bust, which looked nothing like the 2020 pandemic. Modeling on a dozen regime-different events is inherently fragile. Use the signal directionally, expect the timing to be fuzzy, and stack it with other indicators before drawing conclusions.