Multi-Leg 'Combo' Contracts Elevate Prediction Market Volume Under CFTC Rules

Stacked event contracts that bundle multiple predictions into a single all-or-nothing payout are driving a surge in headline trading volume across U.S. prediction platforms, despite accounting for a small fraction of actual transaction activity. According to reporting by CNBC Business (https://www.cnbc.com/2026/10/06/prediction-market-combo-contract-volume.html), federal accounting guidelines for binary derivatives allow these low-cost, high-payout bets to register outsized volume figures on exchange ledgers.

The format, analogous to traditional parlay bets on sportsbooks, has expanded quickly since the start of the NFL season. Multi-leg combos accounted for more than 50% of notional volume on Kalshi in September, with sports combinations driving the majority of the total. Combos also captured over 35% of notional volume share across Kalshi's non-sports categories. Competitor Polymarket made combo products a priority following the May launch of its regulated U.S. platform, where combos now represent nearly 50% of daily volume.

The gap between published volume and user activity stems from how the Commodity Futures Trading Commission (CFTC) mandates volume accounting. Prediction market event contracts settle at binary outcomes between $0 and $1. When an order executes, exchanges log $1 of notional volume regardless of the purchase price, because a market maker or counterparty takes the other side to complete the $1 contract structure. On long-shot combo wagers, speculators can risk pennies for payouts well above $1, generating hundreds or thousands of dollars in reported volume as market makers absorb the opposing side.

Chris Park, founder and researcher at market data firm MSR Decode, told CNBC Business that multi-leg contracts help exchanges report elevated figures with minimal cash commitment. A CNBC analysis of Kalshi trading on Sept. 27 showed single contracts averaged less than 47 cents in cash per trade, compared to approximately 9 cents per contract on combos. Platform data compiled on Dune showed combos generated 58% of Kalshi's trading volume in September while making up less than 13% of its total transactions.

The expansion of sports-related prediction contracts has coincided with pressure on conventional digital sportsbooks. Over the past year, shares of FanDuel parent Flutter Entertainment and DraftKings have fallen 70% and 45%, respectively. However, Bernstein analyst Ian Moore noted that comparing prediction market notional volume to a sportsbook's 'handle'—the total dollar sum wagered by bettors—can lead investors to misjudge the relative scale of the two sectors. Rich Jaycobs, an independent regulatory adviser, noted that because sportsbooks report only the direct wager while CFTC rules require logging both sides of a contract, calculated prediction market volume on out-of-the-money or combo positions can appear 20 to 100 times larger than the same wager on a sportsbook.

Kalshi spokesperson Jack Such stated that the platform's notional volume does not overstate activity, adding that participants looking for alternative measurements can consult other metrics. Kyle Gesuelli, Kalshi's head of revenue and analytics, highlighted 'taker volume'—specifically retail demand buying 'yes' outcomes on combo positions—as a more precise gauge of genuine trader activity by measuring direct liquidity consumption rather than market-maker volume.