Prediction markets: trading yes and no shares against other people

On every large venue the taker pays, makers rarely do, and the fee depends on the price as well as the size of the trade. Here are the published formulas, where C is the number of shares or contracts and p is the price.

Polymarket (international)

Fee = C × feeRate × p × (1 - p), with the rate set by category: 0.07 for crypto, 0.05 for sports, economics, culture and weather, 0.04 for politics, finance and tech, and 0 for geopolitics. On 100 shares at $0.50 that is $1.75 on a crypto market, $1.25 on sport and $1.00 on politics. Polymarket charges no deposit or withdrawal fee and pays part of its fees, 15-25% depending on category, back to makers as rebates.

Kalshi

Taker fee = 0.07 × C × P × (1 - P), rounded up, per the fee schedule effective 7 July 2026. Some markets add a maker fee with a 0.0175 multiplier. There is no settlement or membership fee and no ACH fee; card deposits cost up to 2%, and crypto deposits go through a third-party processor that sets its own charges. 100 contracts at $0.50 cost $1.75, the same as Polymarket's crypto rate.

Limitless

On its new trading venues Limitless charges takers 5% × (1 - price) of the trade value and makers nothing. Buying $50 of shares at $0.50 costs 2.5%, or $1.25. Written out per share, that is 0.05 × C × p × (1 - p): the same dollar fee as Polymarket's sports rate. Its other market types use other rates: 0.40% to 3.00% on legacy order-book buys, a flat 0.40% on AMM markets, and a 2% pool fee, paid to the creator, on user-created markets.

The practical point: a trade near 50/50 carries the highest fee, and a round trip (buy, then sell before resolution) pays it twice if both orders are takers. Posting limit orders avoids most of the cost on every venue above.

The two names come up together, but they are different kinds of business serving different people.

Americans who want Polymarket use a separate product. Polymarket US is run by QCX LLC, a CFTC-designated contract market, and has been fully launched since May 2026 by the company's own account. The figures above apply to the international site only.

The international site is non-custodial: you trade from your own wallet, and a transfer sent to the wrong address or network cannot be reversed. Its geographic restrictions cover the US, UK, Australia, several EU countries and four Canadian provinces, and some countries, Poland and Singapore among them, can only close existing positions. Kalshi's CFTC filing shows its designation, and it is the US venue listed below.

Both match you with another person and take a fee instead of setting a margin. The differences are in how prices are shown, when the fee is charged and how the venue is regulated.

• Price format. A share price is a probability; exchange odds are its inverse. A $0.40 share equals decimal odds of 2.5, and a $0.25 share equals 4.0.
• When the fee bites. Prediction markets charge per trade, win or lose. Exchanges such as Betfair, Smarkets and Matchbook charge commission only on net winnings in a market, so a losing bet costs nothing extra.
• Regulation. In the US, prediction markets are event contracts under the CFTC. In Britain, the Gambling Commission treats them as betting.
• Markets. Exchanges centre on sport and racing; prediction markets list politics, crypto prices, economics and culture alongside sport.

The lines are blurring. Smarkets runs politics markets on its exchange, and Matchbook partnered with ADI PredictStreet on prediction markets around the 2026 World Cup. Our peer to peer betting guide covers back and lay betting and exchange commission in full, and head to head fantasy covers the US skill-contest alternative on sport.

Prediction markets in the UK. The Gambling Commission's February 2026 guidance says prediction markets would appear to be betting intermediaries, akin to a betting exchange. An operator cannot call itself non-gambling to avoid that, unlicensed ones should not target or transact with British consumers, and there are criminal offences for operating without a licence. Polymarket's international site blocks the UK. The licensed route for British users is an exchange's politics and event markets, such as those on Smarkets. More in our UK legality guide.

Prediction markets in the US. Kalshi and Polymarket US are CFTC-designated contract markets, which makes them federally regulated exchanges. Whether states can still apply gambling law to sports contracts is unresolved as of October 2026:

• The 3rd Circuit sided with Kalshi against New Jersey on 6 April 2026, at the preliminary injunction stage.
• The 9th Circuit ruled against Kalshi in Nevada on 28 August 2026.
• The 6th Circuit ruled against Kalshi in Ohio and Tennessee on 25 September 2026.
• New Jersey's Supreme Court petition, No. 26-299, is pending, with a response due on 9 November 2026.

The CFTC also proposed a rule on 10 June 2026 for event contracts that involve gaming. Elsewhere, an offshore platform's terms decide who it accepts, not whether trading is legal where you live; the country table below and the P2P gambling laws guide cover the rest.