Kalshi adds volume tags and accuracy scores to election contracts before midterms

CNBC reported on 6 October that Kalshi is launching three features on its election contracts, less than a month before the midterms. The platform will tag election markets with less than $10,000 in volume as low volume, publish Brier scores that measure the accuracy of its market probabilities against actual outcomes, and show individual trades on election contracts live in an activity feed.

Kalshi said it added the features after noting that election traders were participating in markets covering local races more than national ones, according to CNBC. Co-founder and CEO Tarek Mansour called the midterms the "first meaningful prediction market election" and said the platform's election markets have grown six times faster than football markets this year compared with the year before, CNBC reported. CNBC reported that Kalshi's internal data indicates more people are viewing its midterm markets than are trading them, by a ratio of five to one. In July 2026 the platform released a "Midterms Hub" that allows anyone to view traders' odds on markets tied to U.S. Senate and House of Representatives races.

Combos are multiple contracts stacked together that pay out only if all of them win, similar to parlays on traditional sportsbooks, and CNBC reported they have grown in popularity. In September, combos accounted for more than 50% of notional volume on Kalshi, driven by the start of the NFL season, and were overwhelmingly made up of combinations of sports contracts. At rival Polymarket, combos are now nearly 50% of daily volume on its U.S. exchange, which officially launched in May 2026, according to CNBC.

Chris Park, a researcher and founder of MSR Decode, a firm that analyzes prediction market data, said the multi-leg contracts are "helping [Polymarket and Kalshi] claim a higher number with lower realistic cash output," according to CNBC. CNBC reported that the Commodity Futures Trading Commission, the federal regulator overseeing prediction markets, requires exchanges to report volume, and that platforms count a trade as $1 of notional volume because all event contracts have binary outcomes between $0 and $1. A CNBC analysis of Kalshi trades on 27 September found the average cash placed on a single contract was less than 47 cents, while the average per combo contract was about 9 cents. Data on Dune showed combos made up 58% of Kalshi's trading volume in September but less than 13% of total transactions, and CNBC reported that how combos are measured is not always clear to the public and can make platforms look as though they are growing faster than they are.

CNBC reported that the rising popularity of sports-related event contracts has hurt traditional online sportsbooks, including FanDuel parent Flutter Entertainment and DraftKings, whose shares have fallen 70% and 45% respectively over the past year. Ian Moore, an analyst at Bernstein, said he has spoken to investors who see the notional number, compare it to handle in sports betting and argue that prediction markets have already exceeded the scale of sports betting. CNBC reported that a handle in a sportsbook measures the total dollar amount wagered, while prediction markets count both sides of a trade.