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Prediction markets sharply increased the odds of a September Federal Reserve rate hike after core inflation rose more than expected on Sept. 11. DeFi Rate’s cross-venue probability for a 25-basis-point increase climbed from 63.7% to 81.3% in 24 hours, while total volume across the decision reached $192.6 million on Kalshi and Polymarket Global. Polymarket US also self-certified contracts for the meeting Friday.
The odds of a Federal Reserve rate hike surged Friday after a hotter-than-expected measure of underlying inflation left policymakers with little evidence that price pressures are easing.
Prediction markets tracked by DeFi Rate put the probability of a 25-basis-point increase at 81.3% as of 2:43 p.m. ET Friday, up from 63.7% at roughly the same time Thursday. The 17.6-percentage-point swing followed an immediate repricing across every major prediction platform in the tracker. The September decision has now generated $192.6 million in total volume across Kalshi and Polymarket Global.
The Federal Open Market Committee meets Sept. 15-16, according to the Federal Reserve calendar. A quarter-point increase would lift its benchmark rate from the current 3.50%-3.75% range.
The move leaves the September decision increasingly focused on whether the Fed begins another tightening sequence, rather than whether it raises rates at all. It is a sharper version of the September hike shift traders began pricing after July’s hold.
Prediction markets repriced a Fed hike within an hour
The shift began immediately after the CPI report was released at 8:30 a.m. ET. DeFi Rate’s aggregated probability of a 25-basis-point hike rose from approximately 60.5% before the report to 78.6% in the first hourly snapshot afterward. It reached 81.3% later Friday.
The cross-venue probability that the Fed would leave rates unchanged fell from 35.5% to 18.1% over the same period.
Trading accelerated alongside the price movement. Kalshi reported approximately $10.1 million in displayed 24-hour volume across its 25-basis-point hike and no-change contracts. The equivalent Polymarket contracts generated approximately $12.3 million in 24-hour volume. Kalshi’s daily total rose $7.5 million, to 4.1 times the prior 24-hour period.
Polymarket US has also self-certified its own September Fed decision contracts, which began trading Friday. The contracts add another federally regulated U.S. view on the meeting, but their volume is kept separate from the $192.6 million combined total for Kalshi and Polymarket Global.
Traditional interest-rate markets moved even further. CME FedWatch briefly put the probability of a quarter-point increase at 91% before it settled near 87%, up from 72% Thursday, <a href="https://www.reuters.com/world/us/us-consumer-inflation-picks-up-august-2026-09-11/” rel=”nofollow noopener” target=”_blank”>Reuters reported.
Core inflation changed the outlook
The Bureau of Labor Statistics said consumer prices rose 0.4% in August after increasing 0.1% in July. Headline inflation held at 3.4% from a year earlier.
The more consequential figure for the Fed was core inflation, which excludes food and energy. Core CPI rose 0.3% for the month, above the 0.2% increase economists expected and its largest advance since April.
Gasoline prices jumped 3.9% and accounted for more than one-third of the monthly headline increase. The broader energy index rose 2.1% in August and 16.3% over the past year, adding to concern that higher transportation and production costs could spread into other parts of the economy.
Shelter costs also accelerated, rising 0.3% after a 0.1% increase in July. Airline fares climbed 2.7%, lodging away from home rose 2.4% and transportation services increased 0.5%.
The report followed firm producer-price data Thursday. Economists now expect the Fed’s preferred core Personal Consumption Expenditures measure to have risen 0.3% in August the reports weakened the argument that officials could remain patient while inflation moved steadily toward the Fed’s 2% target
Attention turns to what follows the hike
Chair Kevin Warsh said in August that policymakers would “have work to do” if they could not gain confidence that inflation was returning to 2%. Friday’s report did not provide that confidence, particularly with energy costs rising and core monthly inflation accelerating.
Sung Won Sohn, a finance and economics professor at Loyola Marymount University, said the Fed could not afford to let an energy shock become “an everything shock.” Reuters reported that most economists see another increase as possible in October or December as energy costs spread through transportation, goods and consumer inflation.
That leaves one meaningfulofficials treat the current energy shock as temporary or conclude that waiting risks allowing it to become embedded in broader prices and inflation expectations
Following the Fed decision market
Kalshi’s five-contract Fed decision series shows how trading has built across each 2026 meeting. September remains open.
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Source: defirate.com