Thousands who gambled on the U.S. election are looking forward to a potential payout of about $450 million from online gambling sites after Donald Trump was elected president in a stunning comeback – but some may have to wait to collect their haul.

Online election betting sites exploded into view in the final weeks of the election due to the way former President Trump’s odds on so-called “prediction markets” sharply diverged from opinion polls, which had the race locked in a dead heat.