Several accounts on the online platform Polymarket laid bets on a US-Iran ceasefire over the weekend that appeared to show signs of insider knowledge, according to experts.

Eight accounts, all newly created around 21 March, bet a total of nearly $70,000 (£52,000) on there being a ceasefire. They stand to make nearly $820,000 if a such a deal is reached before 31 March.

An account that made the same bet was created shortly before the US struck Iran on 28 February. It also placed a winning bet on those strikes, which raised similar questions around insider trading, and so far has bet on nothing else.

The new accounts all appear to have been created late last week, around the time when the US president, Donald Trump, appeared to first double down on war with Iran, then suggest in an-after markets Truth Social post that he was considering “winding down” military operations.

The wallets “definitely [look like] someone with some degree of inside info,” said Ben Yorke, formerly a researcher with CoinTelegraph, now building an AI trading platform called Starchild.

Polymarket accounts are anonymous, and it is extremely difficult to trace the owners of the crypto wallets that laid the bets.

But online crypto watchers and experts suggested that the bets bore the signs of insider trading – both because they bought their positions at market price, and because some of the accounts looked like they could belong to a single investor attempting to conceal their identity by splitting their bet between multiple wallets.

“Typically, when you see wallet splitting and deliberate attempts to obfuscate identity, it’s one of two scenarios: either a very large investor trying to shield their position from market impact, or insider trading,” said Yorke.

Polymarket’s own rating of the probability of a ceasefire before 31 March increased significantly in the past few days, from 6% on 21 March to 24% by Monday. More than $21m is currently being wagered on this outcome.

Online prediction markets such as Polymarket and Kalshi are rapidly becoming a feature of modern warfare. Timely bets laid this year suggest insiders may be using them to profit from secret information, such as Trump’s plans to kidnap the Venezuelan leader, Nicolás Maduro, or the timing of US-Israel attacks on Iran.

Polymarket, whose investors include a venture capital firm owned by Donald Trump Jr, has faced criticism and regulatory scrutiny over potentially facilitating war profiteering and insider trading. A New York Times story recently found that while the company described itself as “News 2.0” – a parallel source of information harnessing the power of prediction markets – its own social media feeds are full of falsehoods.

On several Discord channels devoted to Polymarket, users and automated bots on Monday traded tips on how to monetise the war – including arbitrage between different platforms, and following users with a history of good bets.

One post suggested users wager “YES” on “US x Iran ceasefire by March 31” because three historically profitable traders on the platform had bet “yes,” and a historically unprofitable trader had bet “no”.

Insider knowledge may not be enough to win this particular bet on Polymarket, as it requires both the US and Iran to agree that a ceasefire has been reached.

The rules for settling the bet read: “For the purposes of this market, an ‘official ceasefire agreement’ requires clear public confirmation from both the United States government and the government of Iran that they have agreed to halt military hostilities against one another.”

Polymarket has been approached for comment.