Smarkets is a London-based betting exchange licensed by the Great Britain Gambling Commission. Like Betfair it matches users against each other rather than taking positions itself, and it charges commission on net winnings rather than shading the odds.
Its distinguishing feature is a flat 2% commission on net winnings, applied uniformly rather than varying by market or by a loyalty tier. On a market you win often, that difference against a higher base rate compounds.
UK residents who trade often enough for the commission difference to matter, and who do not need the very deepest book. Smarkets is materially smaller than Betfair, so on major elections you will usually find better liquidity elsewhere, and on a narrow market you may find no counterparty at all.
A displayed price is only as real as the money behind it. On a thin exchange market the quoted odds can imply a probability nobody is actually willing to trade at, which is a different situation from a thin market on a venue with a market maker.
For where Smarkets sits legally alongside Betfair and the offshore venues, read which prediction markets are legal in the UK.
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