Kalshi had 164,079 open markets on 29 October 2026, grouped in 16,066 events, with 1.38 billion contracts of open interest between them. Ten events hold 50.1% of that: the 2028 Democratic presidential nominee (165 million contracts), the 2027 Pro Football champion (157 million), control of the US House in 2026 (58 million), the 2028 presidential winner (53 million) and the 2026 midterm balance of power (50 million), followed by the 2028 Republican nominee, college football, the 2027 Pro Basketball champion, the Texas Senate race and the NFL MVP. At the other end, 98,399 markets (60.0%) have no open interest. Open interest counts contracts held and not yet settled, so it shows where positions sit, unlike volume, which shows what traded.
A few contracts, many markets
The median market with any open interest holds 348 contracts. The 100 largest markets hold 41.4% of all open interest and the 1,000 largest 81.5%. Sports makes up 60.3% of open markets but 41.4% of open interest, probably because many of its markets are short-lived game contracts, though the data do not show why; it accounts for 59.6% of the 104.8 million contracts traded in the past 24 hours on markets still open. Elections is the reverse: 15.8% of open markets, 45.2% of open interest and 28.4% of 24-hour volume, consistent with long-dated positions on political outcomes such as the 2028 race. The three 2028 presidential events alone hold 19.4% of everything open.
Crypto and the short contracts
Crypto is 2.9% of open markets and 2.2% of open interest, but 3.4% of 24-hour volume, and only 27.8% of its open markets have open interest. That fits the short contracts we examined in our 15-minute crypto volume post: positions are opened and settled within minutes, so little stays open. Politics, economics, entertainment and science and technology each have 67% to 86% of their open markets with positions held.
Key facts
Source: Kalshi trade API /markets (status open, combination markets excluded), field open_interest_fp, and /events and /series for names and categories; 164,079 markets pulled 18:12 UTC on 29 October 2026. Kalshi documents open_interest_fp as the number of contracts bought on a market without netting.
Totals: 16,066 events, 1,376.9 million contracts of open interest, 65,680 markets with open interest above zero (40.0%), 104.8 million contracts traded in 24 hours on the open markets.
Top events by open interest: 2028 Democratic nominee 165.0m (12.0%), 2027 Pro Football champion 156.8m (11.4%), US House 2026 58.5m (4.2%), 2028 presidential winner 53.4m (3.9%), midterm balance of power 49.8m (3.6%), 2028 Republican nominee 48.2m (3.5%), college football champion 47.7m (3.5%), 2027 Pro Basketball champion 41.6m (3.0%), Texas Senate 38.2m (2.8%), NFL MVP 31.3m (2.3%).
Categories (Kalshi’s own labels): share of open markets, open interest and 24-hour volume: Sports 60.3%, 41.4%, 59.6%; Elections 15.8%, 45.2%, 28.4%; Crypto 2.9%, 2.2%, 3.4%.
Not covered: combination (multivariate) markets, settled markets, and any dollar value of positions, since the API gives contracts, not what holders paid.
How to read it
Open interest is measured in contracts, each of which pays $1 if it settles in the holder’s favour, so the figure is not an amount of money at risk and cannot be compared directly with volume in dollars. Because it is counted without netting, it can overstate the net exposure a holder has taken. Both open interest and the ten-event list change daily as games settle and new markets open: in our first pull two days earlier, on 27 October, Kalshi had 147,243 open markets and the same ten events held 50.9%.
Why it matters for GambleFi
Where positions stay open is a different test of a prediction market from how much it trades, in the same way that holders and trading tell different stories for an iGaming token in our holder concentration check. For Kalshi’s volume by category see our sports share analysis, for how it compares with other venues the venue count, and for more figures the statistics page. This is a data report, not investment advice.