A bettor made nearly half a million dollars on the ouster of Venezuela’s president just before it was officially announced, raising questions about whether someone profited from inside knowledge of the US operation.

Wagers on Polymarket, a crypto-powered platform, that Nicolás Maduro would be out of power by the end of January rose in the hours before President Donald Trump announced on Saturday the Venezuelan leader had been seized.

One account, which joined the platform last month and took four positions, all on Venezuela, made more than $436,000 (£322,000) from a $32,537 bet.

It remains unclear who placed the bet. The anonymous account had a blockchain identifier of letters and numbers.

Polymarket data shows traders put the odds of Maduro’s exit at just 6.5% in the afternoon of Friday 2 January.

But the odds had jumped to 11% by shortly before midnight and surged in the early hours of 3 January, indicating a sudden change in positions just before Trump posted on Truth Social that Maduro was in US custody.

Polymarket did not immediately respond to a request for comment.

Dennis Kelleher, CEO of Better Markets, a non-partisan group that advocates for financial reform, told the BBC’s US partner CBS: “This particular bet has all the hallmarks of a trade based on inside information.”

A handful of other Polymarket users also made tens of thousands of dollars from wagers on Maduro’s capture.

Some lawmakers are starting to take note.

Congressman Ritchie Torres, a Democrat from New York, introduced a bill on Monday that seeks to ban government employees from making trades on prediction markets if they have “material nonpublic information” related to a bet.

Prediction markets have surged in popularity in the US in recent years, with companies like Polymarket and Kalshi letting users bet on everything from sports to politics.

The industry’s leading companies attracted hundreds of millions of dollars in wagers on the outcome of the 2024 US presidential election.

The industry faced scrutiny from regulators under the Biden administration. But it has received a warmer welcome during the Trump presidency.

Donald Trump Jr, the president’s son, serves in advisory roles at Kalshi and Polymarket.

Insider trading is illegal in the stock market, but there are fewer regulations in prediction markets.

A spokesperson for Kalshi said the prediction site “explicitly prohibits insider trading of any form, including government employees trading on prediction markets related to government activity”.