World Cup bettors wagered $14B on prediction markets as manipulation concerns mount

Football fans wagered more than $14 billion on the 2026 FIFA World Cup through prediction markets Polymarket and Kalshi, according to an analysis published Wednesday by Bellingcat, underscoring the explosive growth of an industry now facing mounting questions about its integrity.

The findings arrived the same day Bloomberg published an investigation revealing how cheaply and easily prediction markets can be manipulated, with one user spending $44,000 to push a political candidate's odds from the low teens to 96% on Polymarket.bloomberg+1

Record Volumes, Concentrated Winnings

On Polymarket, users traded $10 billion on World Cup outcomes — $5.7 billion on individual matches and $4.3 billion on which country would win the tournament. Kalshi accounted for an additional $4.3 billion. The largest single market was the Spain vs. Argentina final, which drew $212 million in trading volume on Polymarket alone.bellingcat

Bellingcat's analysis also found that just 1% of Polymarket accounts collected 86% of all winnings, while the bottom 50% of winners shared just 0.1% of profits. The most successful account earned more than $13 million, while the biggest loser lost $11.6 million. More than 14,500 traders who bet on two or more games lost every wager.bellingcat

The pattern aligns with a Wall Street Journal News Corp ↗ 1.11% analysis from May showing that a small number of accounts on prediction platforms — often professionals using algorithmic trading — take home most winnings.wsj

Manipulation and Regulatory Pressure

Bloomberg's investigation, reported by Liam Vaughan, found that a user called "Fine-Tributary" bought $44,000 worth of "yes" contracts for a California gubernatorial candidate named Mahan, pushing the price from the low teens to 96 cents — implying near-certain victory — in a market where traditional polls placed the candidate at around 4%. While the odds eventually fell back, the episode illustrated how thinly traded political markets can be distorted with relatively modest sums.bloomberg

The Commodity Futures Trading Commission issued its first formal guidance on prediction market manipulation in March, asking exchanges to engage with regulators before opening markets that might be vulnerable to manipulation and insider trading. A separate Bloomberg review found that at least 34,000 trades on Polymarket between August 2025 and June 2026 were flagged as potential insider trades.bloomberg+2

An Industry at a Crossroads

Polymarket's U.S. platform is on track to record $4.5 billion in trading volume for July, according to a report from The Block, fueled by World Cup markets, entertainment events, and IPO-linked contracts. The broader prediction market industry processed roughly $50 billion in trading volume during June alone, driven largely by World Cup betting.bitget+1

The surge in activity has drawn attention from lawmakers. Two senators have called for a federal investigation into Polymarket's marketing practices following reporting on deceptive promotional videos. Whether prediction markets can maintain their claim as reliable forecasting tools while absorbing billions in speculative sports and political bets remains the central question regulators now face.facebook