TLDR Polymarket US began testing multi-leg sports contracts on Aug. 5 through an API-only beta that never appeared in its consumer app. The beta logged 16,173 trades worth $7.4 million in volume and $928,093 in stakes. Kalshi collected about $25 million in parlay taker fees during the first 16 days of August. Reports that Kalshi will add maker fees to parlays on Aug. 20 trace back to a trader’s post on X, not to Kalshi. Kalshi’s published fee schedule currently lists no upcoming changes to its parlay pricing.
Polymarket US started processing multi-leg sports contracts, known as parlays, on Aug. 5. The launch came through an API-only beta. It has not appeared in the exchange’s consumer app.
The beta arrived 11 weeks after Polymarket US certified the product with federal regulators. Data from InGame shows 16,173 trades during the test. Total volume reached $7.4 million.
Stakes from the taking side of those trades came to $928,093. Most of the activity happened after Aug. 13. Volume figures count both sides of a trade, so the stake number reflects money actually put up.
The parlay option does not show up in Polymarket’s app. The exchange also has not launched a full desktop site. Documentation for the product sits in a section only visible to approved API users.
A Slow Rollout After Certification
The underlying contract is called the Combinatoric Athletic Outcome Contract. Each leg in the bet must win for the contract to pay out $1.00. If one leg loses, the whole contract pays nothing.
The contract can include between two and 10 legs. Polymarket US filed the product with regulators on May 20. It amended the terms on July 14.
The revised version could not be listed before July 28. The first trade came eight days later, on