Prediction markets usually get quoted as one number: "markets see a 75% chance the Fed holds". There are two big US venues for Fed decisions, Polymarket and Kalshi, and they don't always say the same thing.
At 07:46 UTC on 15 October 2026 I pulled every open market on the Fed's next decisions from both venues' public APIs, with the prediction_markets tool in canli-mcp. The raw output is saved with that timestamp, so every number below can be checked against it.
The October meeting (27 and 28 October)
| Outcome | Polymarket | Kalshi |
|---|---|---|
| No change | 75.5% | 71.5% |
| Hike 25 bp | 24.5% | 27.5% |
| Anything else (cuts, bigger hikes) | under 1% each | under 1% each |
"Probability" here is the middle of the best bid and the best ask, so it is a price, not a forecast. The quotes behind it: Polymarket "No change" 0.75 bid / 0.76 ask and "25 bps increase" 0.24 / 0.25; Kalshi "Fed maintains rate" 0.71 / 0.72 and "Hike 25bps" 0.26 / 0.29.
Three things I noticed
1. Four points apart on the same question. Both books are deep. Polymarket's October event has traded about $40.5 million, and Kalshi's about 11.1 million contracts (each pays $1 if its outcome happens). The spreads are one to three cents, so the gap is bigger than the spread. The two venues differ in fees, in who is allowed to trade on them, and in their exact resolution rules, and any of those can keep prices apart. If you quote "the market", say which one.
2. Kalshi disagrees with itself a little. Kalshi also runs "Fed funds rate after October meeting?" as a ladder of thresholds. "Above 4.00%" traded at 0.22 bid / 0.25 ask (23.5%). The target range is 3.75% to 4.00% today, so getting above 4.00% needs a hike, and the hike outcomes in the other market add up to 28% (27.5% for 25 bp plus 0.5% for more). The two quotes don't even overlap: the best ask for "Above 4.00%" (0.25) is below the best bid for "Hike 25bps" (0.26). The ladder is a much thinner market, about 0.37 million contracts traded against 11.1 million for the main October one, and I haven't checked the two contracts' exact settlement rules, so there may be a reason. If you trade these, I'd like to know what it is.
3. Further out, thinner books. Polymarket's December market has traded about $3.5 million and January's about $0.5 million. At those sizes a single trade can move the price, so read the volume before reading the percentage.
Pull it yourself
canli-mcp is a free MCP server (MIT, no API key). In any MCP client:
npx -y canli-mcp
# Claude Code
claude mcp add canli -- npx -y canli-mcp
Then ask for "prediction markets on the fed decision", or call the tool directly through run_tool:
{ "name": "prediction_markets", "arguments": { "query": "fed decision", "limit": 3 } }
Each row gives the venue, event, market, outcome, probability, bid, ask, last trade, volume and closing date. Polymarket's events also come with their resolution rules, which is where differences like the one in point 2 usually start.
These are traders' prices before fees and the spread, not forecasts and not investment advice, and access to each venue depends on where you live.
The code is on GitHub:
-
arhancanli/canlicapital: every MCP server, including
prediction_marketsinmcp-markets/src/predictions.mjs. - arhancanli/alphac: the strategy research engine.
If this was useful to you, a star on the canlicapital repo helps a small project get found.
Do you watch both venues, or trust one? I'm curious which one people treat as the reference price.
Written with AI assistance. Every number is from the tool output saved at 07:46 UTC on 15 October 2026.
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