Alan Greenspan, the longest-serving Federal Reserve Chair of the modern era, died on June 22, 2026, at the age of 100. His passing has done something that economic textbooks never quite managed: it forced Wall Street to reckon, publicly and loudly, with the ghost of a policy that may never have formally existed.

The “Greenspan put,” the belief that the Fed will swoop in to rescue falling markets by cutting rates or flooding the system with liquidity, is back at the center of a heated debate among economists, traders, and policymakers. And the timing could not be more awkward, given that high inflation has effectively tied the Fed’s hands.

The put that wasn’t (but kind of was)

The idea traces back to the stock market crash of October 19, 1987, when the Dow plunged more than 22% in a single session. Greenspan, who had been Fed Chair for barely two months, responded by flooding markets with liquidity and signaling the central bank stood ready to act. Markets stabilized. A legend was born.

Over the next 18 years at the helm, Greenspan repeated some version of this playbook during multiple crises. Each intervention reinforced the perception that there was a floor under asset prices, a put option written by the most powerful central bank on Earth. In financial parlance, a “put” is a contract that protects the holder from losses below a certain price. The Greenspan put was the market’s collective belief that the Fed would provide exactly that kind of protection, just without the actual contract.

The complicated legacy

Greenspan’s tenure is a study in contradictions. He is credited with anchoring inflation at low levels for nearly two decades and fiercely defending Fed independence, two achievements that central bankers still cite as gold standards. The era of the “Great Moderation,” that long stretch of low volatility and steady growth, happened largely on his watch.

But the flip side is brutal. Critics argue that Greenspan’s deregulatory instincts and willingness to keep rates low for extended periods fostered the conditions that inflated the housing bubble. When that bubble burst, the resulting 2008 financial crisis saw nearly 10 million homes lost.

The consensus among economists today is that no formal Fed put policy exists. It never did. But the market perception of one is powerful enough to function as if it were real.

Why inflation changes everything

During Greenspan’s era, inflation was low enough that cutting rates to support falling markets didn’t carry major trade-offs. Today, that calculus is completely different. Cutting rates to cushion a stock market decline could pour fuel on an already stubborn inflation problem. The Fed is stuck between two uncomfortable options: let markets fall and risk economic damage, or intervene and risk making inflation worse.

If a severe market downturn threatens broader economic stability, say a credit freeze or a cascade of corporate defaults, the Fed may feel compelled to act regardless of inflation. But the bar for that intervention is almost certainly higher than it was during the Greenspan years.