Polymarket Had the September Fed Hike at 87.5%: Every 2026 FOMC Decision, Scored

Polymarket called the Federal Reserve's 16 September decision, and with confidence. A day before the statement and again an hour before it, the 25 basis-point hike traded at 87.5% and no change at 11.5%, with every other outcome below 1%. The Committee raised the target range by a quarter point to 3.75–4.00%, by 12 votes to none. Scored across all five outcomes, the reading comes to 0.029 at both checkpoints, where 0 is a perfect call.

The next decision is announced at 18:00 UTC on 28 October, at the end of the 27–28 October meeting. At 16:40 UTC on 25 September Polymarket priced a second 25 bp hike at 62.5% and no change at 37.5%. Vultax's forecast record will lock those prices 14 days, 7 days, 24 hours and 1 hour before the statement and score them on this page once the result is out.

Both checkpoints were fixed in the forecast record before they came due, and each probability is the midpoint of Polymarket's best bid and ask at the checkpoint minute. The 14-day and 7-day checkpoints are missing because the record opened on 12 September, after they had passed; a missed checkpoint stays missed.

Almost all of the doubt sat on no change rather than on a cut. The 50+ bp cut contract had no bid at either checkpoint, so it enters the score at zero; its ask was 0.1¢.

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Before the September statement an October hike was the minority view: 23.5% on 26 August and 34.5% an hour before the announcement. The market repriced within two hours, to 47.5% by 20:00 UTC, and stayed above 50% from 18 September. Its largest move since came on 23 September, from 53.5% to 67.5% between 13:00 and 15:00 UTC.

At 16:40 UTC on 25 September the hike stood at 62.5%, no change at 37.5% and a 25 bp cut at 0.45%. Weighting each of the five outcomes by its price gives an expected move of +15.8 basis points. Polymarket prices the December meeting separately, and a 25 bp hike there traded at 70.5%.

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The October meeting was written into the forecast record on 23 September, before any of its checkpoints came due. The event file fixes what is being predicted (the change in the upper bound of the target range, rounded up in size to the next 25 bp as the venue rounds it), the five Polymarket contracts that price it and the four times their prices are locked. Its SHA-256 is printed below, so anyone holding the file can check that it did not change after the prices were known.

Each checkpoint reads the best bid and ask on all five contracts within a minute of its time and stores the raw venue response with its own hash. After the statement the midpoints are scored with the same five-outcome Brier score as September. A one-sided or empty book is recorded as unavailable rather than filled in, and a checkpoint that is not captured stays missed.

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• 14 days out: 14 October 2026, 18:00 UTC
• 7 days out: 21 October, 18:00 UTC
• 24 hours out: 27 October, 18:00 UTC
• 1 hour out: 28 October, 17:00 UTC
• Statement: 28 October, 18:00 UTC (2:00 p.m. EDT)

The figures in this section are the observation the study was first written on, kept as published.

At 07:00 UTC on 6 September, Polymarket's September Fed decision event priced a 25 basis-point hike at 49.5% and no change at 49.5%, with a 25 bp cut at 0.4%. $99 million had traded on the event since it opened and $2.87 million of it in the previous day. Ten days before the meeting, that was a coin flip.

It did not stay one. Between 12:00 and 13:00 UTC on 11 September, the hour of the August CPI release, the hike contract rose from 57.5% to 79.5%, and it was 87.5% on the morning of the decision.

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In the seven days to 6 September Vultax's pipeline observed 13,659 fills worth $5.90 million on the three September contracts, from 5,120 wallets. 131 of those wallets belong to the round-the-clock cohort from the cadence study, 2.6% of the wallets on the contract, and they made 19.8% of the trades and 8.3% of the notional. Across all of Polymarket that cohort makes 58% of trades; on the Fed markets it makes a fifth. By Polymarket's standards the Fed is unusually human.

The fills arrive in bursts around the data. Friday's jobs report was the tallest hour of the week before the study; the August CPI print landed on 11 September at 12:30 UTC, the last scheduled macro release before the meeting.

Four things decide the next reading, on 27–28 October 2026.

• The September employment report on 2 October and September CPI on 14 October, both at 12:30 UTC. The August CPI hour moved the September hike contract 22 points, and the 14-day checkpoint is locked six hours after the CPI print.
• The no-change contract. At 37.5% on 25 September it carried nearly all of the doubt; the two cut contracts together were under 1%.
• The blackout. Fed officials stop speaking publicly about policy from 17 October, the second Saturday before the meeting, so the last speeches before the 7-day checkpoint set the tone.
• Post, do not take. Polymarket charges its trading fee to the taker; a resting order that someone else fills pays none.

The strip at the top of this page is republished every ten minutes from Polymarket's event data and price history for the next scheduled decision, the Treasury bill curve against the effective federal funds rate, the Cleveland Fed's daily inflation nowcast, the Fed's press and speech feeds, and Vultax's record of Polymarket fills. Each figure carries the time it was observed, which is not the same as the time the pack was published. When Vultax's fill record is behind, the strip says so rather than presenting the prices and the fill-derived figures as equally fresh.

The four figures are Polymarket's prices for a 25 bp hike and for no change, the probability-weighted expected move in basis points across all five outcomes, and the dollars traded on the event in the last day. The table beneath them shows all five outcomes now and 24 hours earlier. The Vi IQ beneath that scores the domains that apply to a single venue; arbitrage potential needs two venues and is shown as unavailable.

The September statement was short and unanimous: 12 votes to none for a quarter-point increase, activity "expanding at a solid pace", inflation "elevated", and the hike described as support for "a timelier return" to the 2% goal.

The bill market points the same way. At the 24 September close the three-month Treasury bill yielded 4.24% against an effective federal funds rate of 3.88%, 36 basis points above it. August CPI was 3.4% higher than a year earlier, and the Cleveland Fed's nowcast put September at 3.57%.

Polymarket prices are the CLOB price history for each contract's Yes token at hourly fidelity, and Gamma event data for the latest reading; checkpoint prices are the forecast record's quote midpoints. Fill counts come from Vultax's copy of public on-chain fills and undercount fills not yet ingested at read time. Nothing here is a forecast of the decision, and nothing here is financial advice.