PANews reported on October 25 that according to CoinDesk, a trader on Polymarket bought a large number of Trump "win" contracts, causing a brief mispricing in the 2024 U.S. presidential election market. The trader spent more than $3 million to buy 4.5 million contracts in a short period of time, pushing the probability of Trump's victory to 99%, far higher than the 63% given by the actual market at the time.
The pricing anomaly was caused by Polymarket's on-chain order book mechanism. In one $275,000 order, the trader was filled at 99% odds, while other orders were filled at 65.9 cents and 62.7 cents respectively. Polymarket's dynamic order book adjusts prices with each trade, which can cause severe slippage for large trades and temporarily distort the actual odds.
As of now, Trump’s chance of winning on Polymarket is 63%, while Kamala Harris’s chance of winning is 36%. The market has accumulated more than $2.2 billion in trading volume, making it the largest market on the platform.
