The FBI was probing the possibility that Polymarket had engaged in illegal betting during the presidential election when officers conducted a dawn raid this week.
Shayne Coplan, the 26-year-old CEO of the betting agency which correctly predicted the outcome of the race to the White House, was ordered to hand over his phone and electronics on Wednesday.
His Soho home was raided in the early hours on Wednesday, but Coplan was not arrested and has not been charged.
Sources claimed the FBI were investigating whether his startup accepted bets from users within the US, which would breach a 2022 agreement he'd made with the government, according to Bloomberg.
In January 2022, the Commodity Futures Trading Commission settled a dispute with Polymarket ordering the startup pay a $1.4million penalty for operating unregistered 'bet on your beliefs' wagers.
As part of that agreement, Polymarket vowed to prevent US-based traders from placing bets on the platform.
Outside of the US, users can bet an unlimited amount of money on candidates of their choice.
Polymarket has maintained there are security measures in place to seek out and block American users from betting on the platform.
Shayne Coplan, the 26-year-old CEO of the betting agency which correctly predicted the outcome of the race to the White House , was ordered to hand over his phone and electronics on Wednesday
Polymarket signaled for weeks that Trump would win, and the once low-profile site turned out to be right - despite raising eyebrows of many experts
In the days leading up to the election, a French account holder bet approximately $30million on Trump to win the election, which sparked concerns it could skew the President-elect's perceived popularity.
Hours after the raid, Coplan broke his silence about the investigation, slamming the 'current administration' for targeting him.
'It's discouraging that the current administration would seek a last-ditch effort to go after companies they deem to be associated with political opponents,' he wrote on Elon Musk's X.
'We are deeply committed to being non-partisan, and today is no different, but the incumbents should do some self-reflecting and recognize that taking a more pro-business, pro-startup approach may be what would have changed their fate this election.
'Polymarket has provided value to 10's of millions of people this election cycle, while causing harm to nobody.
'We're deeply proud of that. I'm also proud to say that the future of America, and in particular American entrepreneurship, has never been brighter.'
Musk himself, who was one of the most outspoken and generous donors for Trump's campaign, responded to the post, writing: 'Indeed.'
Separately, Coplan wrote 'new phone, who dis?', seemingly making light of the revelation his phone was seized as part of the search.
Prediction prodigy Shayne Coplan (pictured) and his start-up Polymarket turned out to be more accurate than pollsters as traders bet on an easy Donald Trump victory
But in the aftermath of his predictions, the CEO has now had his phone and electronics seized by the FBI
An insider with knowledge of the investigation said the decision to execute the search warrant as part of a dawn raid was 'grand political theater at its worst.'
'They could have asked his lawyer for any of these things. Instead, they staged a so-called raid so they can leak it to the media and use it for obvious political reasons,' the source told the New York Post.
'This is obvious political retribution by the outgoing administration against Polymarket for providing a market that correctly called the 2024 presidential election,' the source added.
Polymarket signaled for weeks that Trump would win, and the once low-profile site turned out to be right - despite raising eyebrows of many experts.
Coplan said in a post on X after the results were announced: 'Make no mistake, Polymarket single-handedly called the election before anything else. The global truth machine is here, powered by the people.'
Polymarket said it is a 'fully transparent prediction market.'
'We charge no fees, take no trading positions, and allow observers from around the world to analyze all market data as a public good.'
Critics cast doubt on Polymarket's reliability and how representative it is of the American public.
The site has humble beginnings, with Coplan sharing a photo of his 'office' four years ago which was actually in his bathroom.
The young entrepreneur has kept his personal political leanings under wraps, but he recently went for breakfast with Florida Governor Ron DeSantis.
Coplan said the company's profile was boosted after it correctly called Joe Biden's withdrawal from the race.
Coplan was reportedly not arrested or given a reason for the raid, but it is thought to be linked to his accurate predictions which outsmarted traditional polls
However, he claims his site remains strictly non-partisan.
'We're just market nerds who think prediction markets provide the public with a much needed alternative data source,' Coplan previously said. 'Polymarket is not about politics.'
Polymarket, Kalshi and other betting platforms have quickly emerged as a way to put money on elections and gauge who's ahead, after successive cycles in which pollster forecasts crashed and burned.
Bettors place 'trades' on a candidate and get a payout if they back the correct outcome.
More and bigger bets on a front-runner raise a candidate's odds, while at the same time reducing bettors' returns.
Polling, which involves canvassing voters about how they plan to vote and then processing that data, had suggested a tight race, including in the seven swing states that decided the contest.
But they undercounted Trump's support nationwide. He went on to win the popular vote, the electoral college, and all seven swing states.
DailyMail.com has contacted the FBI for comment.