ACDC flags 556 Polymarket wallets as likely insider traders

A new report from the Anti-Corruption Data Collective (ACDC) has identified 556 Polymarket accounts, which it calls “Orcas.”

These accounts reportedly place small, targeted bets on events with low odds and win more than 75% of the time.

What did ACDC find out about Polymarket?

The Anti-Corruption Data Collective (ACDC) has released a report called “Classifying Insider Trading Risk,” which examined 78,496 longshot bets placed by 12,355 wallets on Polymarket. ACDC defines a longshot as a wager of more than $2,500 at a price of 35 cents or less, meaning the outcome has a 35% chance or worse.

From that pool, the researchers carved out four groups: Orcas, Whales, Bots and “Small Fish.” There were 556 reported Orca wallets that bet in only a handful of markets and topics, yet they won at a very high success rate above 75%.

Whales, at 3,278 wallets, trade at high volume across many markets. Bots, 760 of them, look at least partly automated, while the remaining 7,761 accounts are the Small Fish.

In an earlier April report, ACDC found that across all of Polymarket, only 14% of longshot bets win, but in political markets, the rate climbs to 25%, and in military and defense markets, it reaches 52%.

Michelle Kendler-Kretsch and David Szakonyi, who wrote the report, counted $9.3 million in winning longshot bets from military markets alone.

Why is insider trading on Polymarket a national security issue?

ACDC found that when betting on major military events, Orcas place their wagers first, then Whales and Bots trail behind, similar to how experienced traders observe the public blockchain and copy insider-like moves in real time.

This “copycat” trading is legal, but it can broadcast insider activity to the world.

For instance, when an Orca placed a bet on U.S. military action in Iran hours before the June 2025 strikes, a Bot and a Whale made copycat bets of $200,000 and $100,000, respectively.

The same blockchain transparency that allows for copycat trading will also allow foreign militaries and intelligence services to act on market signals.

Tracing an Orca account back to a person is complicated because the money trail is pseudonymous, and the exchanges that hold funds for thousands of customers will have to be subpoenaed to provide any information.

ACDC concluded that banning the highest-risk market categories outright is the only solution.

There have been several other incidents of insider trading on prediction platforms. In April, the Justice Department charged a U.S. Army soldier named Gannon Ken Van Dyke, accusing him of staking roughly $33,034 on Venezuela contracts using classified details of the raid that captured Nicolás Maduro, then collecting about $409,881.

In May, prosecutors in the Southern District of New York charged Google engineer Michele Spagnuolo with using internal company data to win $1.2 million on Polymarket.

Bubblemaps also recently stated on CBS’s “60 Minutes” that it had traced nine linked accounts that won more than $2.4 million in total across more than 80 Iran war bets at a 98% win rate.

“Luck alone cannot explain those numbers,” Bubblemaps CEO Nicolas Vaiman said.

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