International / unresolved · Direct U.S. connection
Polymarket Saw Over $600 Million in Post-Election Trades Flagged as Suspicious
Prediction market Polymarket experienced over $600 million in trading volume on Ethiopian and Romanian election markets after results were known, a significant portion of which experts suspect to be market manipulation [1][7][10][11][12][15].
Original PrimaryBrief article graphic. Not a photograph of the event.
THE PRIMARY BRIEF
01 · The primary finding
Prediction market platform Polymarket saw over $600 million in trading volume on election markets for Ethiopia and Romania that experts suspect to be "wash trading".
02 · The primary evidence
Reports in October 2026 detail that a significant portion of trading on these markets occurred after election results were settled, with one market showing 99.6% suspicious activity in certain weeks.
03 · Why it matters
This activity raises concerns about the integrity of prediction markets and their potential for manipulation, highlighting regulatory challenges for platforms like Polymarket.
16 cited sources · 16 independent publishers
Prediction market platform Polymarket saw over $600 million in trading volume on election markets for Ethiopia and Romania after the election results were already decided, with experts identifying this activity as suspected "wash trading". This trading involved pairs of accounts repeatedly buying and selling contracts to each other, creating an illusion of high market activity.
This suspected manipulation raises concerns about the integrity of prediction markets and their ability to accurately reflect public sentiment or future events. It also highlights the challenges platforms like Polymarket face in maintaining fair trading environments amidst attempts to exploit their systems for personal gain, potentially influencing how such platforms are regulated.
What the records show
Similar anomalies were observed in the market for Romania's 2024 election. An algorithm developed by Barnard College economics professor Rajiv Sethi and his colleagues flagged nearly all trading volume on an older Romanian market as suspicious, with the share of such transactions reaching as high as 99.6% in certain weeks. Experts define wash trading as engaging in "transactions to give the appearance that purchases and sales have been made, without incurring market risk or changing the trader's market position". Researchers suggest this activity was motivated by "airdrop farming" or "activity farming," where traders inflate volume to qualify for potential future cryptocurrency token allocations from Polymarket. Columbia Business School Professor Yash Kanoria noted that prediction market platforms have experienced significant artificially inflated trading activity. Allen Sirolly, one of the report's authors, stated that wash trading does not require large amounts of capital and found no evidence of the exchange's involvement.