Why bookmakers are fighting Trump and prediction markets in the US

Prediction markets in the US have been growing fast, with combined trading volume on the two biggest platforms, Kalshi and Polymarket, reaching $48.4 billion in August alone. That matters for high-risk payments because the fight is now about whether these platforms are financial venues or just another form of gambling.

1. The two main players, Kalshi and Polymarket, are expanding quickly and signing deals with top sports leagues and teams. At the same time, their user base is growing, which is exactly why state authorities are pushing back.
2. State officials say the activity is no different from the gaming industry. The platforms say the opposite: they present themselves as financial exchanges where users trade contracts on outcomes, not place bets.
3. The product itself is simple enough to explain and complicated enough to litigate. A contract price reflects the market’s estimate of the probability of an event, and that price moves as participants revise their expectations. The examples now include elections, interest rates, oil prices, and sports outcomes such as whether a team will win a match or an UFC fighter will win a bout.
4. The argument has a long history. The text traces it back to 19th-century London “bucket shops,” then to US courts in the early 20th century, which treated the business as illegal gambling and banned it after finding that operators manipulated quote delays and prices to strip players of their money.
5. The modern betting market did not disappear. After the US Supreme Court decision in 2018 opened the door for states to legalize sports betting, American betting expanded rapidly, and prediction markets gained momentum alongside it.

The current volume figure is the key number here: $48.4 billion in August on Kalshi and Polymarket. For PSPs, acquirers, and banks, that is not a niche experiment anymore; it is a market with enough scale to attract sports partnerships, regulatory attention, and the kind of category fight that tends to decide who gets banked, who gets shut out, and under which license.