Prediction markets are betting on events, and the NFL season has turned them into a bigger draw than anyone expected. Last month, Kalshi, one of the largest prediction markets, saw more than half of its trading volume come from “combos” — contracts that pay out only if all of several events happen at once. The NFL season drove the surge, and now Kalshi’s combo volume accounts for more than 50% of its notional volume.
Kalshi’s numbers are striking. Combos made up 58% of trading volume in September, according to data on Dune, but they were less than 13% of total transactions. That means a small number of big trades moved the needle far more than everyday betting did.
Sports-related combos alone made up over 35% of Kalshi’s total volume share. Polymarket, another prediction platform, shows a similar pattern. Combos are nearly 50% of daily volume on Polymarket U.S., also driven by NFL growth.
What a Combo Is
A combo is a stack of contracts tied together. All of them have to win for the bettor to get paid. It is a way to bet on a whole game, a whole series of games, or a set of related events at once.
Kalshi’s numbers show how dominant they have become. The September figure means that more than half of what Kalshi recorded as trading was from these bundled bets. The smaller transaction count tells a different story: fewer people placed them, but the stakes were higher.
Sportsbooks have noticed. FanDuel parent Flutter Entertainment and DraftKings both saw stock drops over the past year, down 70% and 45%, respectively. The drop is tied to prediction market competition.
Notional Volume vs. Taker Volume
Notional volume is the total value of all contracts traded, regardless of whether they settled as wins or losses. Taker volume is the amount of money actually put at risk by traders.
Kalshi’s spokesperson, Jack Such, says notional volume does not overstate activity and points to other metrics for those interested. Ian Moore of Bernstein notes investors may confuse prediction market notional volume with sports betting handles, which measure different things.
The distinction matters for anyone following the market. A handle is a measure of the total amount bet on a single outcome. Notional volume includes every contract, whether it pays out or not.
Kalshi and Polymarket both track taker volume as a better measure of actual trader activity. That is a sensible position. Traders want to know what they are risking, not just what the total exposure looks like.
The Cost of Trading
A single contract trade on Kalshi averaged less than 47 cents in cash in September. Combo trades averaged about 9 cents. That suggests traders are using combos to place larger bets without placing more individual trades.
The difference is notable. A trader can put $100 on a single combo for the price of a handful of individual contracts. That changes the economics of betting.
The Analyst View
Rich Jaycobs, an independent advisor to prediction markets, says prediction markets can show dollar volumes 20 to 100 times greater than sportsbooks because of how each reports volume. The comparison is not apples to apples, but it captures the scale of the difference.
Ian Moore of Bernstein notes investors may confuse prediction market notional volume with sports betting handles, which measure different things. That is a fair warning. Comparing the two without understanding what each measures is easy to do.
What the Numbers Mean
Kalshi’s combo volume is a signal that prediction markets are becoming more popular. The NFL season provided the content, and the platform responded by offering a product that suits how fans want to bet.
The smaller transaction count is worth noting. Fewer people are placing these bets, but the size of each trade is much larger. That is a different kind of engagement, and it changes how the market operates.
Kalshi’s 58% figure for September is the standout number. More than half of its trading was from these bundled bets. That is a remarkable share for a single product type.
The Stock Drop Question
The stock drops at FanDuel parent Flutter Entertainment and DraftKings are real. Both companies saw declines over the past year, down 70% and 45%, respectively. The source ties the drop to prediction market competition.
The numbers are dramatic. A 70% drop is a significant loss for any company. A 45% drop is serious for DraftKings.
A Fairer Measure
Kalshi and Polymarket both track taker volume as a better measure of actual trader activity. That is a reasonable approach. Traders want to know what they are risking, not just what the total exposure looks like.
Notional volume is the standard metric for prediction markets. Kalshi argues it does not overstate activity and points to other metrics for those interested.
Where the paper stands
The paper backs Kalshi’s continued growth in sports betting combos and is against any new licensing regime that would make startup entry too costly for smaller prediction market firms. The danger is big tech dominance, not the technology itself. Kalshi’s numbers show the appeal of these stacked bets: more than half of its trading volume came from combos last month, and sports-related combos alone made up over 35% of its total volume share. The smaller transaction count tells a different story — fewer people placed them, but the stakes were higher.
Kalshi’s growth through combos shows what a small firm can do when it offers a product fans want. The paper supports narrow rules against direct harm, such as forcing companies to disclose safety failures they hid, and opposes broad rules that hand the market to the incumbents. A licensing regime would freeze today’s leaders in place and lock out whoever would have challenged them. The stock drops at FanDuel parent Flutter Entertainment and DraftKings, down 70% and 45% over the past year, are real, but they are tied to prediction market competition, not some failure Kalshi concealed.
Kalshi’s spokesperson, Jack Such, says notional volume does not overstate activity and points to other metrics for those interested. That is a reasonable approach, and Kalshi and Polymarket both track taker volume as a better measure of actual trader activity. The distinction between notional volume and taker volume matters for anyone following the market. Traders want to know what they are risking, not just what the total exposure looks like. The paper wants Kalshi to keep growing its combos while avoiding the moat that licensing regimes create around the market.
Key Facts Box
- Kalshi’s combos accounted for more than 50% of notional volume last month, driven by the NFL season
- Combos were 58% of trading volume in September, per data on Dune
- Sports-related combos made up over 35% of Kalshi’s total volume share
- FanDuel parent Flutter Entertainment and DraftKings saw stock drops of 70% and 45% over the past year
- A single contract trade on Kalshi averaged less than 47 cents in cash in September; combo trades averaged about 9 cents
- Rich Jaycobs says prediction markets can show dollar volumes 20 to 100 times greater than sportsbooks
Comparison Table
| Metric | Kalshi | Polymarket |
|---|---|---|
| Combo share of notional volume | More than 50% | Nearly 50% |
| Combo share of trading volume | 58% in September | Data not specified |
| Sports-related combos share | Over 35% | Data not specified |
| Taker volume tracking | Yes | Yes |
Kalshi’s position is straightforward. The company uses notional volume as its standard metric and points to other measures for those who want a fuller picture. The company’s spokesperson, Jack Such, says notional volume does not overstate activity.
Polymarket tracks taker volume as a better measure of actual trader activity. That is a reasonable approach. Traders want to know what they are risking, not just what the total exposure looks like.
The two platforms agree on this much. Kalshi’s spokesman says notional volume does not overstate activity and points to other metrics for those interested. Polymarket also tracks taker volume.
Source material: “How event contract bundles are boosting volume on prediction markets,” CNBC.
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