{ "schemaVersion": "vultax-public-research-data-v1", "articleUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi", "datasets": [ { "title": "Scored: the 16 September decision", "columns": [ { "name": "Checkpoint", "unit": null }, { "name": "Polymarket", "unit": null }, { "name": "Kalshi", "unit": null }, { "name": "Outcome", "unit": null }, { "name": "Brier, Polymarket / Kalshi", "unit": null } ], "rows": [ [ "24 hours out — 15 Sep 18:00 UTC", "87.5%", "86.5%", "Hike, 25 bp", "0.029 / 0.037" ], [ "1 hour out — 16 Sep 17:00 UTC", "87.5%", "87.5%", "Hike, 25 bp", "0.029 / 0.031" ] ], "measurementContext": "Probability on the 25 bp hike contract at each checkpoint, taken from the forecast record before the announcement. Brier is the multi-outcome score summed over each venue’s contracts on the decision — four on Polymarket, two on Kalshi — so the sums are not strictly comparable; lower is better and a perfect call is 0.", "sources": [ { "label": "Polymarket: Fed decision in September?", "url": "https://polymarket.com/event/fed-decision-in-september-762", "note": "Event and contract prices, Gamma and CLOB APIs; read 2026-09-06" }, { "label": "Kalshi: KXFEDDECISION-26SEP", "url": "https://kalshi.com/markets/kxfeddecision", "note": "Hourly candles via the public trade API; read 2026-09-06" }, { "label": "Polymarket trading fees", "url": "https://docs.polymarket.com/trading/fees.md", "note": "Formula and per-category rates" }, { "label": "Kalshi fee schedule", "url": "https://kalshi.com/fee-schedule", "note": "Taker formula" }, { "label": "Vultax: Kalshi vs Polymarket odds gap, measured", "url": "https://vultax.com/research/kalshi-polymarket-open-interest-by-category", "note": "The July matched-pair study" }, { "label": "Vultax: 1.6% of Polymarket wallets never sleep", "url": "https://vultax.com/research/polymarket-wallets-that-never-sleep-trading-cadence", "note": "The round-the-clock cohort" }, { "label": "Federal Reserve — Minutes of the FOMC, July 28–29, 2026", "url": "https://www.federalreserve.gov/monetarypolicy/fomcminutes20260729.htm", "note": "9–3 to hold at 3½–3¾%; Hammack, Kashkari and Logan preferred a quarter-point hike; inflation 'elevated' with energy supply shocks; staff saw inflation risks skewed to the upside." }, { "label": "J.P. Morgan Wealth Management (Chase) — September 2026 rate hike now expected amid energy shocks (5 Aug 2026)", "url": "https://www.chase.com/personal/investments/learning-and-insights/article/september-2026-rate-hike-now-expected-amid-energy-shocks", "note": "Futures priced roughly a 65% chance of a September hike in early August; oil near $80 with the Strait of Hormuz still disrupted." }, { "label": "Krause — Calibration and Forecast Accuracy of Macroeconomic Prediction Markets: Evidence from Kalshi, 2025–2026 (SSRN)", "url": "https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7117919", "note": "594 Kalshi macro markets, 1,860 observations, nine series: overall Brier 0.0987; federal-funds-rate markets near-perfectly calibrated (0.0001); unemployment-rate markets the weakest (0.1302); one-hour horizon 0.0812 against 0.1587 at thirty days, as summarised in the abstract." }, { "label": "Coinpaprika — Polymarket expands beyond prediction markets with 20x leverage perps (Sep 2026)", "url": "https://coinpaprika.com/news/polymarket-expands-beyond-prediction-markets/", "note": "Perpetual futures launched 3 September 2026 with up to 20x leverage; 67 markets within hours; U.S. traders barred. Kalshi's bitcoin perpetuals went live 3 June 2026." }, { "label": "Finance Magnates — Polymarket rolls out U.S. app after CFTC green light, starting with sports", "url": "https://www.financemagnates.com/forex/polymarket-rolls-out-us-mobile-app-after-cftc-green-light-starting-with-sports-events/", "note": "Polymarket US launched 2 December 2025 on the QCEX designation acquired for $112 million; the invite waitlist was removed in May 2026; iOS only at the time of writing." } ], "measurement": { "kind": "observed", "temporalCoverage": "2026-09-15/2026-09-16", "population": "Polymarket and Kalshi September 2026 FOMC decision contracts", "methodology": "Quote midpoints read at two checkpoints fixed in advance, 24 hours and 1 hour before the 18:00 UTC announcement, and scored against the published outcome as a sum of squared errors over each venue's contract set." }, "id": "section-scored-16-september-2026-table", "kind": "published-table", "description": "How Polymarket and Kalshi priced each 2026 FOMC decision, scored against the outcome. Both venues had the 16 September hike at 87.5% an hour out; the multi-outcome Brier was 0.029 on Polymarket and 0.031 on Kalshi. Next decision 27–28 October.", "articleUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi", "sectionUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi#section-scored-16-september-2026", "publishedAt": "2026-09-06", "modifiedAt": "2026-09-16", "version": "f97b0342bf0cb1c056f4c3be2724c93a9663424f1107c0aee1de7e84cbf06d14", "isLive": false, "limitations": "Published research snapshots and calculations; these exports do not contain current quotes or live account data. Observation windows and populations are stated in the source captions and methodology. Missing metadata is unknown, not zero. Prices are the venues' quoted probabilities at the stated read time, not Vultax's view, and can change at any moment. Fill figures describe public on-chain activity observed by Vultax. Nothing here is a forecast or financial advice.", "downloads": { "json": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.json?dataset=section-scored-16-september-2026-table", "csv": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.csv?dataset=section-scored-16-september-2026-table" } }, { "title": "Probability of a 25 bp hike, Polymarket vs Kalshi", "columns": [ { "name": "Category", "unit": null }, { "name": "Polymarket", "unit": "%" }, { "name": "Kalshi", "unit": "%" } ], "rows": [ [ "08-07", 36.5, 35 ], [ "08-08", 35.5, 35 ], [ "08-09", 35.5, 33 ], [ "08-10", 43.5, 45 ], [ "08-11", 39.5, 40 ], [ "08-12", 32.5, 34 ], [ "08-13", 27.5, 31 ], [ "08-14", 24.5, 26 ], [ "08-15", 24.5, 26 ], [ "08-16", 24.5, 27 ], [ "08-17", 27.5, 31 ], [ "08-18", 28.5, 29 ], [ "08-19", 27.5, 27 ], [ "08-20", 27.5, 29 ], [ "08-21", 30.5, 32 ], [ "08-22", 30.5, 31 ], [ "08-23", 31.5, 32 ], [ "08-24", 34.5, 34 ], [ "08-25", 32.5, 33 ], [ "08-26", 32.5, 32 ], [ "08-27", 30.5, 30 ], [ "08-28", 50.5, 50 ], [ "08-29", 44.5, 47 ], [ "08-30", 52.5, 53 ], [ "08-31", 54.5, 56 ], [ "09-01", 57.5, 60 ], [ "09-02", 53.5, 54 ], [ "09-03", 42.5, 45 ], [ "09-04", 49.5, 52 ], [ "09-05", 49.5, 50 ], [ "09-06", 49.5, 49 ] ], "measurementContext": "Last quoted price each day, 6 August to 6 September 2026. Polymarket from the CLOB price history; Kalshi from hourly candle closes.", "sources": [ { "label": "Polymarket: Fed decision in September?", "url": "https://polymarket.com/event/fed-decision-in-september-762", "note": "Event and contract prices, Gamma and CLOB APIs; read 2026-09-06" }, { "label": "Kalshi: KXFEDDECISION-26SEP", "url": "https://kalshi.com/markets/kxfeddecision", "note": "Hourly candles via the public trade API; read 2026-09-06" }, { "label": "Polymarket trading fees", "url": "https://docs.polymarket.com/trading/fees.md", "note": "Formula and per-category rates" }, { "label": "Kalshi fee schedule", "url": "https://kalshi.com/fee-schedule", "note": "Taker formula" }, { "label": "Vultax: Kalshi vs Polymarket odds gap, measured", "url": "https://vultax.com/research/kalshi-polymarket-open-interest-by-category", "note": "The July matched-pair study" }, { "label": "Vultax: 1.6% of Polymarket wallets never sleep", "url": "https://vultax.com/research/polymarket-wallets-that-never-sleep-trading-cadence", "note": "The round-the-clock cohort" }, { "label": "Federal Reserve — Minutes of the FOMC, July 28–29, 2026", "url": "https://www.federalreserve.gov/monetarypolicy/fomcminutes20260729.htm", "note": "9–3 to hold at 3½–3¾%; Hammack, Kashkari and Logan preferred a quarter-point hike; inflation 'elevated' with energy supply shocks; staff saw inflation risks skewed to the upside." }, { "label": "J.P. Morgan Wealth Management (Chase) — September 2026 rate hike now expected amid energy shocks (5 Aug 2026)", "url": "https://www.chase.com/personal/investments/learning-and-insights/article/september-2026-rate-hike-now-expected-amid-energy-shocks", "note": "Futures priced roughly a 65% chance of a September hike in early August; oil near $80 with the Strait of Hormuz still disrupted." }, { "label": "Krause — Calibration and Forecast Accuracy of Macroeconomic Prediction Markets: Evidence from Kalshi, 2025–2026 (SSRN)", "url": "https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7117919", "note": "594 Kalshi macro markets, 1,860 observations, nine series: overall Brier 0.0987; federal-funds-rate markets near-perfectly calibrated (0.0001); unemployment-rate markets the weakest (0.1302); one-hour horizon 0.0812 against 0.1587 at thirty days, as summarised in the abstract." }, { "label": "Coinpaprika — Polymarket expands beyond prediction markets with 20x leverage perps (Sep 2026)", "url": "https://coinpaprika.com/news/polymarket-expands-beyond-prediction-markets/", "note": "Perpetual futures launched 3 September 2026 with up to 20x leverage; 67 markets within hours; U.S. traders barred. Kalshi's bitcoin perpetuals went live 3 June 2026." }, { "label": "Finance Magnates — Polymarket rolls out U.S. app after CFTC green light, starting with sports", "url": "https://www.financemagnates.com/forex/polymarket-rolls-out-us-mobile-app-after-cftc-green-light-starting-with-sports-events/", "note": "Polymarket US launched 2 December 2025 on the QCEX designation acquired for $112 million; the invite waitlist was removed in May 2026; iOS only at the time of writing." } ], "measurement": { "kind": null, "temporalCoverage": null, "population": null, "methodology": null }, "id": "section-original-study-observed-6-september-2026-07-00-utc-chart", "kind": "published-chart", "description": "How Polymarket and Kalshi priced each 2026 FOMC decision, scored against the outcome. Both venues had the 16 September hike at 87.5% an hour out; the multi-outcome Brier was 0.029 on Polymarket and 0.031 on Kalshi. Next decision 27–28 October.", "articleUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi", "sectionUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi#section-original-study-observed-6-september-2026-07-00-utc", "publishedAt": "2026-09-06", "modifiedAt": "2026-09-16", "version": "8ca8bfe343f8e7abc96310d0be0a48753cb060abde4d4f8a36ffb78ff6dbee99", "isLive": false, "limitations": "Published research snapshots and calculations; these exports do not contain current quotes or live account data. Observation windows and populations are stated in the source captions and methodology. Missing metadata is unknown, not zero. Prices are the venues' quoted probabilities at the stated read time, not Vultax's view, and can change at any moment. Fill figures describe public on-chain activity observed by Vultax. Nothing here is a forecast or financial advice.", "downloads": { "json": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.json?dataset=section-original-study-observed-6-september-2026-07-00-utc-chart", "csv": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.csv?dataset=section-original-study-observed-6-september-2026-07-00-utc-chart" } }, { "title": "Polymarket minus Kalshi on the hike contract, cents", "columns": [ { "name": "Category", "unit": null }, { "name": "Gap, cents", "unit": null } ], "rows": [ [ "08-07", 1.5 ], [ "08-08", 0.5 ], [ "08-09", 2.5 ], [ "08-10", -1.5 ], [ "08-11", -0.5 ], [ "08-12", -1.5 ], [ "08-13", -3.5 ], [ "08-14", -1.5 ], [ "08-15", -1.5 ], [ "08-16", -2.5 ], [ "08-17", -3.5 ], [ "08-18", -0.5 ], [ "08-19", 0.5 ], [ "08-20", -1.5 ], [ "08-21", -1.5 ], [ "08-22", -0.5 ], [ "08-23", -0.5 ], [ "08-24", 0.5 ], [ "08-25", -0.5 ], [ "08-26", 0.5 ], [ "08-27", 0.5 ], [ "08-28", 0.5 ], [ "08-29", -2.5 ], [ "08-30", -0.5 ], [ "08-31", -1.5 ], [ "09-01", -2.5 ], [ "09-02", -0.5 ], [ "09-03", -2.5 ], [ "09-04", -2.5 ], [ "09-05", -0.5 ], [ "09-06", 0.5 ] ], "measurementContext": "Daily, last price. The fee floor for a two-leg taker round trip at 50 cents is about 2.75 cents either way.", "sources": [ { "label": "Polymarket: Fed decision in September?", "url": "https://polymarket.com/event/fed-decision-in-september-762", "note": "Event and contract prices, Gamma and CLOB APIs; read 2026-09-06" }, { "label": "Kalshi: KXFEDDECISION-26SEP", "url": "https://kalshi.com/markets/kxfeddecision", "note": "Hourly candles via the public trade API; read 2026-09-06" }, { "label": "Polymarket trading fees", "url": "https://docs.polymarket.com/trading/fees.md", "note": "Formula and per-category rates" }, { "label": "Kalshi fee schedule", "url": "https://kalshi.com/fee-schedule", "note": "Taker formula" }, { "label": "Vultax: Kalshi vs Polymarket odds gap, measured", "url": "https://vultax.com/research/kalshi-polymarket-open-interest-by-category", "note": "The July matched-pair study" }, { "label": "Vultax: 1.6% of Polymarket wallets never sleep", "url": "https://vultax.com/research/polymarket-wallets-that-never-sleep-trading-cadence", "note": "The round-the-clock cohort" }, { "label": "Federal Reserve — Minutes of the FOMC, July 28–29, 2026", "url": "https://www.federalreserve.gov/monetarypolicy/fomcminutes20260729.htm", "note": "9–3 to hold at 3½–3¾%; Hammack, Kashkari and Logan preferred a quarter-point hike; inflation 'elevated' with energy supply shocks; staff saw inflation risks skewed to the upside." }, { "label": "J.P. Morgan Wealth Management (Chase) — September 2026 rate hike now expected amid energy shocks (5 Aug 2026)", "url": "https://www.chase.com/personal/investments/learning-and-insights/article/september-2026-rate-hike-now-expected-amid-energy-shocks", "note": "Futures priced roughly a 65% chance of a September hike in early August; oil near $80 with the Strait of Hormuz still disrupted." }, { "label": "Krause — Calibration and Forecast Accuracy of Macroeconomic Prediction Markets: Evidence from Kalshi, 2025–2026 (SSRN)", "url": "https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7117919", "note": "594 Kalshi macro markets, 1,860 observations, nine series: overall Brier 0.0987; federal-funds-rate markets near-perfectly calibrated (0.0001); unemployment-rate markets the weakest (0.1302); one-hour horizon 0.0812 against 0.1587 at thirty days, as summarised in the abstract." }, { "label": "Coinpaprika — Polymarket expands beyond prediction markets with 20x leverage perps (Sep 2026)", "url": "https://coinpaprika.com/news/polymarket-expands-beyond-prediction-markets/", "note": "Perpetual futures launched 3 September 2026 with up to 20x leverage; 67 markets within hours; U.S. traders barred. Kalshi's bitcoin perpetuals went live 3 June 2026." }, { "label": "Finance Magnates — Polymarket rolls out U.S. app after CFTC green light, starting with sports", "url": "https://www.financemagnates.com/forex/polymarket-rolls-out-us-mobile-app-after-cftc-green-light-starting-with-sports-events/", "note": "Polymarket US launched 2 December 2025 on the QCEX designation acquired for $112 million; the invite waitlist was removed in May 2026; iOS only at the time of writing." } ], "measurement": { "kind": null, "temporalCoverage": null, "population": null, "methodology": null }, "id": "section-fees-liquidity-and-the-price-gap-chart", "kind": "published-chart", "description": "How Polymarket and Kalshi priced each 2026 FOMC decision, scored against the outcome. Both venues had the 16 September hike at 87.5% an hour out; the multi-outcome Brier was 0.029 on Polymarket and 0.031 on Kalshi. Next decision 27–28 October.", "articleUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi", "sectionUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi#section-fees-liquidity-and-the-price-gap", "publishedAt": "2026-09-06", "modifiedAt": "2026-09-16", "version": "e9cd1f2371c27364ea8027a36c447abdf7e0384d20b7e697dcc2653480d3c072", "isLive": false, "limitations": "Published research snapshots and calculations; these exports do not contain current quotes or live account data. Observation windows and populations are stated in the source captions and methodology. Missing metadata is unknown, not zero. Prices are the venues' quoted probabilities at the stated read time, not Vultax's view, and can change at any moment. Fill figures describe public on-chain activity observed by Vultax. Nothing here is a forecast or financial advice.", "downloads": { "json": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.json?dataset=section-fees-liquidity-and-the-price-gap-chart", "csv": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.csv?dataset=section-fees-liquidity-and-the-price-gap-chart" } }, { "title": "Who is trading it", "columns": [ { "name": "Contract", "unit": null }, { "name": "Polymarket", "unit": null }, { "name": "Kalshi", "unit": null }, { "name": "Polymarket volume", "unit": null } ], "rows": [ [ "25 bp hike", "49.5%", "49.0%", "$18.5M" ], [ "No change", "49.5%", "49.0%", "$23.2M" ], [ "25 bp cut", "0.4%", "1.0%", "$30.7M" ] ], "measurementContext": "Read 2026-09-06 07:00 UTC, 6 September 2026. Kalshi tickers KXFEDDECISION-26SEP-H25, -H0, -C25.", "sources": [ { "label": "Polymarket: Fed decision in September?", "url": "https://polymarket.com/event/fed-decision-in-september-762", "note": "Event and contract prices, Gamma and CLOB APIs; read 2026-09-06" }, { "label": "Kalshi: KXFEDDECISION-26SEP", "url": "https://kalshi.com/markets/kxfeddecision", "note": "Hourly candles via the public trade API; read 2026-09-06" }, { "label": "Polymarket trading fees", "url": "https://docs.polymarket.com/trading/fees.md", "note": "Formula and per-category rates" }, { "label": "Kalshi fee schedule", "url": "https://kalshi.com/fee-schedule", "note": "Taker formula" }, { "label": "Vultax: Kalshi vs Polymarket odds gap, measured", "url": "https://vultax.com/research/kalshi-polymarket-open-interest-by-category", "note": "The July matched-pair study" }, { "label": "Vultax: 1.6% of Polymarket wallets never sleep", "url": "https://vultax.com/research/polymarket-wallets-that-never-sleep-trading-cadence", "note": "The round-the-clock cohort" }, { "label": "Federal Reserve — Minutes of the FOMC, July 28–29, 2026", "url": "https://www.federalreserve.gov/monetarypolicy/fomcminutes20260729.htm", "note": "9–3 to hold at 3½–3¾%; Hammack, Kashkari and Logan preferred a quarter-point hike; inflation 'elevated' with energy supply shocks; staff saw inflation risks skewed to the upside." }, { "label": "J.P. Morgan Wealth Management (Chase) — September 2026 rate hike now expected amid energy shocks (5 Aug 2026)", "url": "https://www.chase.com/personal/investments/learning-and-insights/article/september-2026-rate-hike-now-expected-amid-energy-shocks", "note": "Futures priced roughly a 65% chance of a September hike in early August; oil near $80 with the Strait of Hormuz still disrupted." }, { "label": "Krause — Calibration and Forecast Accuracy of Macroeconomic Prediction Markets: Evidence from Kalshi, 2025–2026 (SSRN)", "url": "https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7117919", "note": "594 Kalshi macro markets, 1,860 observations, nine series: overall Brier 0.0987; federal-funds-rate markets near-perfectly calibrated (0.0001); unemployment-rate markets the weakest (0.1302); one-hour horizon 0.0812 against 0.1587 at thirty days, as summarised in the abstract." }, { "label": "Coinpaprika — Polymarket expands beyond prediction markets with 20x leverage perps (Sep 2026)", "url": "https://coinpaprika.com/news/polymarket-expands-beyond-prediction-markets/", "note": "Perpetual futures launched 3 September 2026 with up to 20x leverage; 67 markets within hours; U.S. traders barred. Kalshi's bitcoin perpetuals went live 3 June 2026." }, { "label": "Finance Magnates — Polymarket rolls out U.S. app after CFTC green light, starting with sports", "url": "https://www.financemagnates.com/forex/polymarket-rolls-out-us-mobile-app-after-cftc-green-light-starting-with-sports-events/", "note": "Polymarket US launched 2 December 2025 on the QCEX designation acquired for $112 million; the invite waitlist was removed in May 2026; iOS only at the time of writing." } ], "measurement": { "kind": null, "temporalCoverage": null, "population": null, "methodology": null }, "id": "section-who-is-trading-it-table", "kind": "published-table", "description": "How Polymarket and Kalshi priced each 2026 FOMC decision, scored against the outcome. Both venues had the 16 September hike at 87.5% an hour out; the multi-outcome Brier was 0.029 on Polymarket and 0.031 on Kalshi. Next decision 27–28 October.", "articleUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi", "sectionUrl": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi#section-who-is-trading-it", "publishedAt": "2026-09-06", "modifiedAt": "2026-09-16", "version": "994c3c5e6cbc36a788da4af8bdae329f428bee868ed922d4263aab9b170af13b", "isLive": false, "limitations": "Published research snapshots and calculations; these exports do not contain current quotes or live account data. Observation windows and populations are stated in the source captions and methodology. Missing metadata is unknown, not zero. Prices are the venues' quoted probabilities at the stated read time, not Vultax's view, and can change at any moment. Fill figures describe public on-chain activity observed by Vultax. Nothing here is a forecast or financial advice.", "downloads": { "json": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.json?dataset=section-who-is-trading-it-table", "csv": "https://vultax.com/research/fed-september-decision-coin-flip-polymarket-kalshi/data.csv?dataset=section-who-is-trading-it-table" } } ] }