Kalshi, Polymarket Face Scrutiny Over Trading Volume Patterns
Kalshi attributes activity in Ether perpetuals to liquidity programs, while Polymarket says professional traders exploit pricing differences across international prediction markets.
Trading patterns across Kalshi’s Ether perpetuals and Polymarket International’s low-probability contracts are drawing scrutiny as both platforms report substantial activity in markets with unusual liquidity and probability profiles.
Kalshi said its perpetual-futures liquidity programs compensate market makers for maintaining resting orders rather than generating volume. The company also said hundreds of distinct traders took the other side of flagged trades, while its systems block self-trading and monitor coordinated trading.
“We’ve seen no evidence of collusion or wash trades,” Kalshi said.
Kalshi reported more than 350,000 lifetime perpetual-futures traders and said open interest doubled during the 30 days before its statement. The company launched its first U.S. perpetual-futures products on May 29, 2026. The contracts do not expire and are designed to track underlying asset prices.
Activity on Polymarket International has also centered on contracts with sharply different trading volumes and probabilities. In an Ethiopia prime-minister market, about $170,000 was traded on Abiy Ahmed while his probability stood at 98%. Nearly $56 million was traded on Gedion Timothewos, whose probability remained below 3% for months.
Polymarket International’s 2026 World Cup markets showed a similar pattern. Spain recorded $152 million in trading volume despite being favored, while Egypt recorded $158 million despite remaining below a 0.5% chance of winning.
Polymarket says its international platform records every trade on a public blockchain and monitors trading and wallet activity with machine-learning models, blockchain analytics and surveillance tools. It prohibits wash trading, spoofing, self-dealing and other manipulative conduct on both its international and U.S. platforms.
Polymarket US is a Commodity Futures Trading Commission-designated contract market. Polymarket International operates separately and is not regulated by the CFTC.
Wash trading refers to transactions that create the appearance of market activity without genuine economic exposure. Repeated trade sizes, heavy activity in low-probability contracts and high volume relative to available liquidity can prompt surveillance questions, but those patterns alone do not establish wash trading.
