# 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].

By PrimaryBrief newsroom · Published 2026-10-20T00:12:30.779880Z
Canonical: https://primarybrief.com/article/polymarket-saw-over-600-million-in-post-election-trades-flagged-as-suspicious-58d66649

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" [1][7][10][11][12][15]. This trading involved pairs of accounts repeatedly buying and selling contracts to each other, creating an illusion of high market activity [7][11][12].

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 [12][13].

## What the records show
Over $600 million in trading volume on Polymarket's election markets for Ethiopia and Romania was generated after the outcomes of these elections were known, according to reports in October 2026 [1][7][10][11][12][15]. For the Ethiopian election market, the total trading volume reached $285 million [7][12]. Approximately $284 million of this volume stemmed from pairs of accounts repeatedly buying and selling contracts to one another [7][12]. This activity involved 38,000 trade loops, with a median contract hold time of just nine seconds [7][12]. In contrast to the $173,000 traded on contracts predicting Prime Minister Abiy Ahmed's victory, contracts concerning the appointment of his chief of staff, Shimelis Abdisa, as the next leader, garnered over $41 million in trading, despite Ahmed winning the election [7].

Similar anomalies were observed in the market for Romania's 2024 election [7]. 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 [7][11]. 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" [3][6]. 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 [5][12]. Columbia Business School Professor Yash Kanoria noted that prediction market platforms have experienced significant artificially inflated trading activity [4]. 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 [5].

## The timeline
Trading on the Ethiopian market reportedly continued for 123 days after the election [7]. In December 2024, suspicious trades on Polymarket peaked at nearly 60% of the weekly volume, before declining to under 5% by May 2025 [5]. Reports detailing the $600 million in suspicious trading emerged in October 2026 [1][7][12]. Polymarket announced changes to its market integrity framework in October 2026 [13].

## What changed and for whom
Polymarket responded to the findings by announcing updates to its market integrity framework in October 2026 [13]. These changes include tightening trading safeguards, establishing clearer operating standards across its global decentralized finance platform and its U.S. exchange, and expanding monitoring systems [13]. The company also stated its intention to limit or restrict market categories deemed easily manipulated or ethically sensitive [13]. Polymarket blocked accounts involved in the suspicious Ethiopian trading activity [11][12]. The incidents have contributed to increasing regulatory pressure, with some U.S. states taking action against prediction platforms, alleging they operate as unlicensed gambling services [13].

## What Polymarket has said publicly
Polymarket stated it "immediately flagged this activity, investigated, and blocked the accounts from trading" in response to the Ethiopian market activity [11]. Shana Bautista, a Polymarket representative, confirmed this action [7]. However, the company did not provide an explanation for why these trades were allowed to continue for several months before action was taken [11]. In October 2026, Polymarket announced an overhaul of its market integrity framework to address manipulation concerns [13].

## What we could not confirm
We could not confirm the exact number of accounts Polymarket blocked. The specific dates when Polymarket flagged and blocked the suspicious accounts involved in the Ethiopian market remain unclear. It could not be definitively confirmed that the motivation for these specific wash trading instances was solely "airdrop farming." The identities of the traders involved in the suspected wash trading were not confirmed. The total financial impact of the alleged wash trading beyond the stated volume of $600 million is also unknown.

## Evidence cited
1. Polymarket saw $600 million in election trades after the elections were over (arstechnica.com) — https://arstechnica.com/tech-policy/2026/10/polymarket-saw-600-million-in-election-trades-after-the-elections-were-over/
2. Nearly All Volume on FIFA-Linked Prediction Market Is Circular Trading (www.wsj.com) — https://www.wsj.com/finance/nearly-all-volume-on-fifa-linked-prediction-market-is-circular-trading-549393f3?mod=rss_markets_main
3. Consider the following set of trades executed in quick succession on Polymarket at around 6pm on November 1, just a couple of days before polls opened on election day: This is just a small sample of a string of very similar transactions executed by the same trader at around the same time. (substack.com) — https://substack.com/
4. Columbia Business School's Professor Yash Kanoria spoke with Bloomberg reporter Lydia Beyoud about a new CBS study showing that prediction market platforms—such as Polymarket—have experienced significant artificially inflated trading activity. (columbia.edu) — https://www.columbia.edu/
5. Allen Sirolly, one of the report's authors told Decrypt that the team “don't know (or claim to know) what motivates wash trading on Polymarket, but it is possibly related to airdrop farming.” “Wash trading does not require large amounts of capital, since capital is recycled across multiple trades. We have no evidence that the exchange is involved in any way,” he said. (decrypt.co) — https://decrypt.co/
6. Wash trading is trading with yourself or between colluding accounts to fake volume, price, or activity. (sardine.ai) — https://sardine.ai/
7. Two Polymarket election markets related to Ethiopia and Romania generated more than $600 million in trading volume, with researchers identifying suspected wash trading activity. (ua.news) — https://ua.news/
8. Contracts tied to elections in Ethiopia and Romania saw massive trading volumes after the outcomes were decided. “It's obviously some form of volume… (reddit.com) — https://reddit.com/
9. Contracts tied to elections in Ethiopia and Romania saw massive trading volumes after the outcomes were decided. “It's obviously some form of volume manipulation,” one expert says. (chinewsdaily.com) — https://chinewsdaily.com/
10. Two global election markets on Polymarket drew over $600 million in trading, much of it after the races were decided. In Ethiopia, nearly all the volume came from pairs of accounts buying and selling with each other, which experts call likely volume manipulation. Source — WIRED: https://www.wired.com/story/over-dollar600-million-traded-on-polymarket-election-contracts-after-races-ended Created with ChillBrief: https://chillbrief.com. (youtube.com) — https://youtube.com/
11. An anonymous reader quotes a report from Wired: Prediction market boosters often tout the platforms as barometers of public opinion, or even "truth machines" offering a clearer picture of where things are headed than polling or other data. In 2024, for example, Kalshi beat many pollsters in forecasting the outcome of the US presidential race. But their trading activity can also tell more perplexing stories. Two global election markets on Polymarket's offshore platform, for instance, generated ov (slashdot.org) — https://slashdot.org/
12. Polymarket Election Markets Face Wash Trading Concerns (wisevoter.com) — https://wisevoter.com/
13. The updated rules cover market design standards, resolution criteria, and data sourcing requirements. Polymarket Tightens Trading Rules Amid Manipulation Concerns. Table of Contents. Prediction Market News. Prediction Market News. Polymarket has overhauled its market integrity framework, introducing tighter trading safeguards and clearer operating standards across its global decentralized finance platform and its U.S. exchange. The U.S. exchange operates under compliance oversight by the Commodi (coinmarketcap.com) — https://coinmarketcap.com/
14. Polymarket's rules state that the Ethiopian election market ... Months later, Romania held a new election, but Polymarket ... wash trading on the offshore ... (weex.com) — https://weex.com/
15. Polymarket's Ethiopia & Romania markets rack up $600m post-result. Swipe for more → Polymarket saw over $600m traded on two election markets after the results were already decided, with experts calling it manipulation. Should Polymarket explain how $600m traded after the results were known? Full story on infobets.com - link in bio & in the first comment. #Polymarket #WashTrading #PredictionMarkets #kalshi · View 1 comment · infobetscom. Full story: https://infobets.com/news/polymarket-wash-tradi (instagram.com) — https://instagram.com/
16. Polymarket election markets drew over $600 million, but suspicious trading and post-election contracts raise questions about volume. The post Post-Election Trading Puts Polymarket Volume Under Scrutiny Appeared First on ReadWrite . (groundlevelnews.com) — https://groundlevelnews.com/