Combo Contracts Dominated Prediction Market Volume
Complex trading instruments have claimed a majority share of notional volume on major U.S. prediction platforms.
Updated on Oct. 6, 2026 in Investing
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Combo contracts have surged to account for over 50% of the notional trading volume on platforms like Kalshi and Polymarket U.S. These financial products allow traders to bundle outcomes, driving significant volume metrics despite representing a much smaller fraction of total individual transactions.
Why it matters
Traders often utilize these complex combo contracts to pursue higher potential payouts compared to standard single-event bets. Because exchanges report volume based on regulatory guidance that counts any trade as $1 of notional volume, these bundles disproportionately inflate reported activity levels.
Combo contracts made up 58% of Kalshi's volume in September despite accounting for less than 13% of total transactions. On September 27, traders placed an average of 9 cents on combo contracts, significantly lower than the 47 cents average for single contracts.
The players
Kalshi
This is a U.S.-based prediction market exchange that operates under regulatory guidance from the Commodity Futures Trading Commission.
Polymarket U.S.
This is a prediction market platform that entered the U.S. market in 2026 and utilizes similar notional volume reporting metrics.
Commodity Futures Trading Commission
This is the independent federal agency that oversees derivatives markets and provides the regulatory guidance for volume reporting.
DraftKings
This is a publicly traded sports betting and gaming company that has seen its stock value decline by 45% over the past year.
Flutter Entertainment
This is a global sports betting holding company that has experienced a 70% decline in its stock price over the last twelve months.
The details
Platforms measure any trade as $1 of notional volume, regardless of the actual cash amount a trader risks on the bet. This reporting structure, influenced by Commodity Futures Trading Commission guidance, allows combo contracts to appear as the primary driver of market activity even when the actual capital commitment per trade is low.
Timeline
Polymarket U.S. officially launched its platform in May 2026.
Kalshi trading data was analyzed by CNBC on September 27, 2026.
Combos comprised 58% of Kalshi's total trading volume throughout September 2026.
Market Dynamics
The current trading landscape is heavily influenced by the Commodity Futures Trading Commission regulatory guidance on volume reporting. This methodology creates a disconnect between notional volume and actual cash flow, fundamentally altering how market activity is perceived by investors.
Retail investors should note that notional volume does not reflect the actual amount of capital committed to a trade, potentially creating a false sense of market depth. This discrepancy can complicate risk assessment when evaluating the popularity of specific betting products.
The takeaway
Investors should scrutinize reported volume figures on prediction markets, as they may be inflated by specific bundling structures. Relying on notional volume without considering the average cash commitment per trade can lead to a misunderstanding of actual market liquidity.
Further reading
For more background on market metrics, explore the Investing section.
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