The probability of a September rate hike has surged to 60%

Since early June, the iconic Dow Jones Industrial Average (^DJI -0.70%), benchmark S&P 500 (^GSPC -0.33%), and innovation-powered Nasdaq Composite (^IXIC -0.12%) have rallied to fresh all-time highs. But these gains aren’t reflective of the inflationary headwinds that lie beneath the surface.

In May, the trailing 12-month U.S. inflation rate reached a three-year high of 4.2%, which is more than double the Federal Reserve’s long-term target of 2%. In addition to expected inflationary factors, such as businesses possessing modest pricing power over their goods and services amid an expanding economy, several of President Donald Trump’s policies have contributed to higher inflation, including tariffs and the Iran war.

Persistently elevated inflation has investors questioning whether Fed Chair Kevin Warsh and the Federal Open Market Committee (FOMC) will take action and adjust short-term lending rates to deliver price stability.

The probability of a September rate hike has surged to 60%

As of Aug. 27, the CME Group‘s FedWatch Tool, which uses 30-day Fed Funds futures prices to estimate the probability of federal funds target rate changes at upcoming FOMC meetings, assigned a 35% chance of a rate hike at the Sept. 15-16 meeting.

But following Warsh’s comments at the annual economic symposium in Jackson Hole, Wyoming, on Aug. 28, the odds of a September rate hike have nearly doubled to 60%. Several of Warsh’s to-the-point comments spooked Wall Street and appeared to clarify his and the FOMC’s stance on inflation.

Fed Chair Kevin Warsh says the central bank may need to raise rates if underlying inflation does not return to its 2% target, as financial conditions remain insufficiently restrictive https://t.co/p3RmFyyO8g pic.twitter.com/oemokaCXav

— Reuters Business (@ReutersBiz) August 28, 2026

For starters, Warsh effectively weighed the economic risks of both aspects of the dual mandate, maximum employment and price stability, and determined the latter to be of the utmost importance. While noting that neither the Personal Consumption Expenditures price index nor the Consumer Price Index were perfect, the new Fed chair stated:

Inflation is running above our two percent target. So the Fed’s predominant focus right now should be on prices.

In discussing the Fed’s key principles, Warsh proclaimed that “short-term interest rates are the predominant tool to achieve the dual mandate.” While a surge in long-duration bond yields has worked in the central bank’s favor — higher yields at the long end of the yield curve can increase borrowing costs for businesses and essentially pump the brakes on inflation — Warsh recognizes that the FOMC is ultimately responsible for price stability.

But perhaps the biggest reaction in Fed Funds futures activity, and the reason the odds of a September rate hike surged after the Fed chair’s Jackson Hole speech, was his summation of the central bank’s objectives. Warsh opined:

Here is my standard: We must be confident that underlying inflation is moving to our objective, clearly and at sufficient speed. Otherwise, we have work to do.

In particular, it’s the addition of “at sufficient speed” that likely sent shockwaves through the stock market. Warsh noted that prevailing inflation has been above the Fed’s long-term target of 2% for 65 months. His patience, and that of his FOMC colleagues, for persistently elevated inflation may be wearing thin.

If the FOMC does hike interest rates in September, it may mark the end of Wall Street’s historic artificial intelligence (AI)-driven rally. The stock market is priced for perfection, and anything that could slow the AI infrastructure build-out, such as elevated borrowing costs, can halt Wall Street’s bull market rally in its tracks.