When Plus500 added sports event contracts to its US platform earlier this year, the scale of what was coming was still a projection. The 2026 World Cup has now turned it into a number.Polymarket's flagship "World Cup Winner" market has drawn $4 billion in volume since launching in July 2025, the largest single market in the platform's history, surpassing its 2024 US presidential election contract.Kalshi's equivalent market has crossed $1 billion, with France priced at 34% and defending champions Argentina at 18% as the tournament enters the round of 16.June Rewrote the Industry's NumbersPrediction markets processed more than $50 billion in June, up 75% from May, according to Artemis data. Kalshi accounted for roughly $33 billion, including $7.4 billion in World Cup trades — more than its entire March Madness volume. Polymarket's World Cup activity reached $6.6 billion in June, against $138,000 during the 2022 tournament. Rothera, the Robinhood-backed venue, added around $2 billion.The World Cup is an exceptional catalyst that concentrates liquidity into a few weeks, so the June figures describe the event rather than a new baseline. For firms distributing these products, however, those short-lived spikes are part of the business model.Plus500 Sits in the FlowPlus500 added Kalshi's CFTC-regulated sports contracts, covering NFL, NBA, MLB and other events, to its Plus500 Futures platform shortly before the tournament began. The broker acts as the retail access layer: contracts are listed and resolved on Kalshi, while Plus500 handles onboarding, the interface, and clearing through its Kalshi Klear membership. It also clears for FanDuel Prediction Markets, the CME Group joint venture.Plus500 is therefore exposed to the largest liquidity event prediction markets have seen so far. Retail participation in Kalshi's football contracts runs, in part, through exactly the position Plus500 built in February.Plus500 does not break out its prediction market revenue. Its US business generated about $35 million in quarterly revenue before the tournament, up 45% year over year, driven by the non-OTC offering that includes futures and event contracts.The Bottom LineThe demand side of Plus500's sports betting has been confirmed at a scale few expected in February. The size of the payout is the one number still missing. It will arrive with the broker's next quarterly report.This article was written by Tanya Chepkova at www.financemagnates.com.