Polymarket Trading Volume Exposed: Double-Counting Error Revealed

Polymarket's trading volume has been significantly overstated due to a double-counting error in on-chain data, affecting major analytics dashboards and misleading market analysis.

Recent research has uncovered that Polymarket's reported trading volumes have been significantly inflated due to a double-counting error in on-chain data. The issue stems from how analytics platforms process Polymarket's transaction structure, where both sides of a trade—buyer and seller—are recorded as separate contributions to total volume. This has led to major dashboards and analytics tools, including DeFiLlama, Alium, and Blockworks, aggregating the same transaction twice, thus overstating actual user activity. The bug is not related to wash trading but arises from redundant blockchain events emitted by Polymarket's smart contracts, which are complex and generate multiple "OrderFilled" events for each trade. As a result, both notional and cashflow volume metrics have been affected, misleading analysts and investors about the platform's true market activity. The discovery highlights the need for careful scrutiny of trading volume definitions and suggests that historical data may need to be recalibrated to reflect accurate, single-counted transactions. Until corrections are made, market participants are advised to treat Polymarket's historical volume figures with caution.