After the World Cup wrapped up, prediction markets experienced a noticeable drop in open interest as traders pulled back from event-specific bets. Kalshi, the market leader, held about 59% of total open positions, while Polymarket's share rose from 27% to 41% due to smaller platforms losing capital more rapidly.
Shifting Market Shares Despite Falling Interest
July's data reveals an overall decline in open interest across major platforms. Kalshi’s open positions fell slightly but still exceeded Polymarket’s, with 28,996 active markets compared to Polymarket’s 8,040. However, Polymarket’s market share expanded because smaller competitors shrank faster, not because it attracted new capital. This dynamic meant Polymarket captured a bigger slice of a contracting market rather than growing absolutely.
The total open interest hovered around $923.6 million with a mild 0.04% drop in 24 hours. Polymarket’s stake dropped from $352 million on July 28 to $321 million by early August, including brief rebound attempts that ultimately did not reverse the downward trend. Meanwhile, Kalshi's heavier exposure to event-driven positions, like those tied to the World Cup, made its open interest more sensitive to the event’s conclusion.
Wide Product Range vs. Concentrated Capital
Although Kalshi holds a more extensive catalogue of markets, Polymarket's relative rise signals a concentration of remaining capital within fewer platforms. This suggests that traders are consolidating their activity where liquidity remains highest and opportunities persist beyond the event horizon.
This content is informational and not financial advice.
