Fed Rate Odds Split Across Every Venue: Polymarket Bet on…

The Federal Reserve is scheduled to announce its interest-rate decision at 2:00 p.m. ET on 16 September, with prediction markets and futures-derived tools pricing a 25-basis-point increase as the most likely outcome. In the hours before the 2:00 p.m. ET announcement, Polymarket's September decision market showed the "no change" outcome carrying $52.5 million in cumulative volume against $39.4 million on the leading "+25bp" contract, as of 13:29 UTC (9:29 a.m. ET).The 25-basis-point cut outcome had slightly more volume at $52.8 million, while the 50-plus-basis-point hike and 50-plus-basis-point cut outcomes had $30.4 million and $19.0 million, respectively.

Four Venues, Four Different Numbers

By the morning of 16 September, the headline probability at each venue had converged toward a hike, but the path there and the confidence behind the numbers differed. CME FedWatch, which derives probability from fed funds futures, priced a 25-basis-point increase at roughly 85% to 90%, depending on the timestamp. Polymarket's price-implied probability stood at 88.5%, while DeFi Rate's latest snapshot listed Kalshi at 87.5%, Gemini at 86.5%, ForecastEx at 86.0% and OG at 91.0%. The aggregate probability was 88.2%, according to DeFi Rate.On 12 September, FinanceFeeds reported that Polymarket was pricing a hike at 79.5% while CME FedWatch sat near 86%, a spread of roughly six to ten percentage points that reflected two instruments measuring two different things. Polymarket contracts resolve directly on the Federal Open Market Committee (FOMC) announcement, while FedWatch derives probability from fed funds futures that settle on the monthly effective rate average.Goldman Sachs added its weight to the hike consensus on 15 September, shifting its forecast to a 25-basis-point increase after the August Consumer Price Index (CPI) report showed core inflation rising 0.3% month-over-month against a 0.2% consensus, according to a note reported by Investing.com. According to Investing.com's report of the Goldman Sachs note, the firm raised its terminal-rate forecast to 3.25% to 3.50% from 3.00% to 3.25%. The report said market expectations for a 25-basis-point hike had reached 90%.

The Volume Split Told a Different Story Than the Price

The curiosity of Polymarket's September Fed market was not the final probability but the cumulative volume distribution. At the latest snapshot as of 13:29 UTC (9:29 a.m. ET), the "no change" outcome had attracted about $52.5 million in volume, compared with $39.4 million on "+25bp," $52.8 million on a 25-basis-point cut, $30.4 million on a 50-plus-basis-point hike and $19.0 million on a 50-plus-basis-point cut.Total volume across all five outcomes reached about $193.7 million as of 13:29 UTC (9:29 a.m. ET), according to Polymarket's event page. The volume distribution shows that substantial trading occurred across multiple possible outcomes even as the market increasingly priced a 25-basis-point hike.A trader buying "no change" at 12 cents (88% implied probability of a hike) stood to earn roughly seven dollars for every dollar risked if the Fed held steady. The five-outcome volume split shows that Polymarket's market attracted trading across multiple possible rate decisions, although the data alone does not establish whether individual positions reflected directional conviction, hedging activity, or contrarian bets.

Why Futures and Prediction Markets Can Legitimately Disagree

The two instruments can show different numbers because they measure different things. CME fed funds futures settle on the monthly average effective federal funds rate, so FedWatch must use the futures price and the number of days affected by a policy change to infer the probability of a meeting decision.Polymarket contracts, by contrast, settle directly on the FOMC statement. The different settlement mechanisms can produce differences between the two implied probabilities, but the size and direction of that gap depend on the timing of the meeting and the futures-market pricing.The divergence had been a running theme in 2026. FinanceFeeds reported on 12 September that CPI data repriced FedWatch from 44.4% on 7 August to the mid-to-high 80s by mid-September, while Polymarket's trajectory was shallower, moving from 40.5% to 79.5% over the same period. Chair Kevin Warsh's Jackson Hole speech on 28 August, where he called the 2% inflation target "a firm, fixed target," triggered the sharpest single-day move, pushing Polymarket from 30.5% to 49.5% overnight, according to MacroOdds.

The September Decision Remained Pending, but the Prediction-Market Record is Mixed

The Fed's September decision was still pending at the time of publication, with prediction markets pricing a 25-basis-point increase as the most likely outcome. Any assessment of whether CME FedWatch or Polymarket correctly anticipated the decision should be made after the FOMC statement is released.Polymarket's probability spent most of August below 50%, while its cumulative volume was distributed across multiple outcomes.The question that matters going forward is whether the prediction-market volume split reflected genuine uncertainty that futures pricing obscured, or whether it reflected the different participant base that trades crypto-native event contracts. The next scheduled test arrives at the 28 October FOMC meeting, while CME FedWatch pricing will depend on the outcome of the September meeting and subsequent economic data. Goldman Sachs has projected two rate cuts in 2027, beginning in September of that year.