Smarkets which already runs a betting exchange, is investing about $5 million to create a traditional sportsbook that will first be launched in its home market in coming months, Chief Executive Officer Jason Trost said to Bloomberg.

The main reason we’re building this is to go into the U.S.,” Trost said by phone from Los Angeles, where he’s based. He estimates the market there could be worth $10 billion to $20 billion were it to be fully liberalized.

The closely held operator is one of many online gambling firms positioning themselves to jump into the U.S. should its ban on sports betting be lifted. The Supreme Court is due to rule in coming months on whether to end a federal law that prohibits such gambling, with at least four states having already enacted legislation to legalize and regulate sports betting.

Trost said the company’s aim has been to take sports bets globally since he founded the business about a decade ago.

First comes the U.K., where the online sports betting market is already crowded. Smarkets won’t compile its own odds, instead drawing them from the betting exchange it has already been operating, where users can place wagers on an event and act as the bookmaker. By doing so, Trost expects to be able to offer bigger odds than traditional compilers.

“There’s a huge opportunity in terms of people wanting the best prices, but not wanting to go to the exchanges,” Trost said.

Trost declined to give an exact date for the U.K. introduction, though he’s unlikely to want to miss an expected betting bonanza on soccer’s World Cup that’s due to take place in June and July.