Prediction market statistics: volume, market share and open interest
A sourced Q3 2026 reference for prediction market volume, dollars paid, venue share and open interest, with definitions and coverage notes.
Prediction Frontier recorded $179.6 billion in notional contract volume and $56.1 billion in dollars paid across Kalshi, Polymarket, Polymarket US and Novig for 1 July–30 September 2026. These measure different things: the first counts contracts at their $1 payout value; the second counts what buyers paid for them.
Edition: Q3 2026. Published: 20 October 2026. These are historical figures from PF's published research, with the period and venue coverage stated below. They are not a live market total or a census of every prediction market.
Jump to volume, market share, open interest, sports, definitions or sources and citation.
Prediction market trading volume in Q3 2026
The quarterly aggregate covers Kalshi, Polymarket's international venue, Polymarket US and Novig. Novig's data begins on 4 August 2026. B means billion; M means million. Dates use UTC.
| Metric | Reported figure | Period and coverage |
|---|---|---|
| Notional contract volume | $179.6B | 1 July–30 September 2026; four tracked venues |
| Dollars paid | $56.1B | 1 July–30 September 2026; four tracked venues |
| Notional volume growth | 84.3% | Q3 versus Q2 2026, as reported; coverage includes Novig's Q3 entry |
| September notional volume | $75.5B | 1–30 September 2026; four tracked venues |
| Largest daily notional volume reported in Q3 | $4.19B | 27 September 2026; four tracked venues |
| Kalshi combo notional volume | $67.1B | 1 July–30 September 2026; Kalshi combos only |
Source: PF Q3 2026 Sector Report, executive summary, “The quarter in numbers” and “Market quality”. See the published PDF on page 3, page 4 and page 22.
Kalshi and Polymarket market share
This table uses share of dollars paid during Q3, rather than share of contracts traded. Its denominator is the $56.1B reported across the four tracked venues.
| Venue coverage | Reported Q3 share of dollars paid |
|---|---|
| Kalshi | 71% |
| Polymarket international and Polymarket US, combined | 27% |
| Novig | 1% |
The report rounds these shares to whole percentages, so the displayed values sum to 99%. The combined Polymarket figure should not be attributed to its international venue alone. Novig is included from 4 August.
Source: PF Q3 report, executive summary and chart C03; page 3 and page 5.
Prediction market open interest
Open interest is a point-in-time measure of outstanding positions. The report's figures below cover Kalshi, Polymarket international and Polymarket US. Novig is excluded because open interest was not published in the source used for the report.
| Coverage | Reported open interest | Snapshot date |
|---|---|---|
| Three tracked venues combined | $2.54B | 30 September 2026 |
| Kalshi | $2.18B | 30 September 2026 |
Kalshi therefore represented approximately 86% of this three-venue open-interest total. This is PF's calculation from the rounded published figures: $2.18B divided by $2.54B. It is a different measure from Kalshi's 71% quarterly share of dollars paid.
Source: PF Q3 report, “The quarter in numbers” and chart C03, page 5.
Sports prediction market statistics
The sports analysis covers 29 June–30 September 2026, a weekly reporting window that starts before the calendar quarter. It counts winner markets at $1 face value, with the coverage limits below.
| Sport or market group | Reported notional winner-market volume |
|---|---|
| Tennis | $9.17B |
| MLB | $7.48B |
| World Cup | $5.60B |
| NFL and college football | $4.33B |
| Club soccer | $2.58B |
| Esports | $1.76B |
| Golf | $1.43B |
| WNBA and NBA summer | $1.08B |
| UFC and boxing | $857M |
| Cricket, hockey and other | $643M |
| All groups in this table | $34.93B |
These figures exclude spreads, totals, props, futures and parlays. Polymarket US sport-level data starts on 23 July, Novig's on 4 August, and Polymarket markets under $50,000 are excluded. The World Cup row therefore covers only the part of the tournament inside this window and does not include Polymarket US. Kalshi golf uses tournament-winner markets. Kalshi markets are assigned by close date and the other venues by game date.
Source: PF Q3 report, table T02 on page 13 and methods on page 26. For a different, trade-level weekly view, read our analysis of Polymarket's $299 million sports week; its period and measurement should not be added to this table.
What do these statistics measure?
Notional volume and dollars paid
Notional volume counts each contract traded at its $1 payout value. Dollars paid multiplies the number of contracts by the execution price. For example, 100 contracts bought at 20¢ produce $100 in notional volume and $20 in dollars paid, before fees. This is an illustration of the definitions.
Both are trading-flow measures. A contract can change hands more than once, so neither is a count of unique capital deposited. Dollars paid is not exchange revenue or trader profit. Low-priced combos and parlays can generate a large contract total relative to the amount buyers pay.
Open interest and order-book depth
Open interest measures positions that remain open at a given time. It should not be added to volume over a period. Order-book depth concerns the orders available to trade at specified prices; in the report's depth analysis it measures the cost of buying through resting sell orders to move the price by a specified amount.
Our liquidity analysis explains why depth and open interest can move differently. For contract prices and payouts, start with how prediction markets work.
Wallets and users
This edition does not publish a combined number of prediction market users. The Q3 report's user-level analysis follows Polymarket wallets, and one person can control several wallets. Those observations should not be labelled as people or added to account counts from other venues. The saved cohort results used in the report end on 9 September, so they do not cover a full September of wallet activity.
Sources, coverage and how to cite this page
The tables reproduce PF's published Q3 analysis. The source report, by Andrew Lujan Odera and Edwin Munyui, was published on 15 October 2026. Download the full report for charts, methods and its source list.
The report uses DeFi Rate daily venue files, compiled with AllTop, for volume, dollars paid and open interest. Sports figures use exchange APIs and Novig exchange data. Appendix B records partial coverage and missing observations, including three Polymarket days filled from monthly totals. The report's public feed excludes Kalshi perpetuals. These tables reproduce the published research rather than a new pull of current provider data.
The original data provider's volume tracker and methodology are separate, changing resources. Their current totals can have different dates and venue coverage from this historical edition. PF's dashboard methodology describes the separate Markets service; when using dashboard figures, check each displayed source date and status.
Suggested citation: Prediction Frontier (2026), “Prediction market statistics: volume, market share and open interest”, Q3 2026 edition, published 20 October 2026, https://predictionfrontier.com/markets/items/prediction-market-statistics. Cite the relevant table's period and venue coverage alongside the figure.
For a chart, data extract or research enquiry, send PF a data request with the venues, period and fields you need.
Update log
20 October 2026: First edition, based on the published Q3 2026 report. New editions will be recorded here when the source research is updated.