Open interest on prediction markets drops by 47.6% after the World Cup

Open interest on the major prediction markets falls sharply in July 2026. Of the $2.1 billion on 6 July, only $1.1 billion remains at the end of the month, a decline of 47.6%. The conclusion of the World Cup plays a major role in this, as figures from CryptoRank show.

In brief:

• Total open interest on prediction markets falls from $2.1 billion to $1.1 billion in July 2026.
• Kalshi remains market leader with around 59% of open interest, but loses some ground to Polymarket.
• The end of the World Cup mainly draws capital away from Kalshi, which held more event-driven money.

Sharp decline after the World Cup

On 6 July, open interest on prediction markets still stands at $2.1 billion. In the weeks that follow, a steady decline sets in: on 13 and 20 July it stabilises around $1.4 billion, but towards the end of the month it drops further to $1.1 billion. That is a total decline of 47.6% in a single month.

The main explanation is the end of the World Cup. Around major sporting events, relatively large amounts of capital flow into prediction markets from people who want to speculate on the outcome of matches and tournaments. As soon as such an event is over, that capital largely disappears again.

Kalshi stays ahead, Polymarket gains market share

Although both platforms lose ground in absolute terms, market shares are moving in the other direction. Kalshi sees its share decline slightly from around 62% to 59%. Polymarket, by contrast, rises from roughly 27% to 41%. This shift is mainly because capital is leaving smaller platforms and partly flowing to Polymarket.

The World Cup had a greater impact on Kalshi than on Polymarket, simply because more event-driven money was concentrated there. Nevertheless, Kalshi firmly holds the leading position with nearly 60% of total open interest. However, its lead over Polymarket is visibly shrinking.