Congressional market study highlights low price-shifting costs and concentrated trading

Research from the Anti-Corruption Data Collective (ACDC) found that 96 percent of congressional prediction markets with live order books could have their prices shifted five cents for 3,500 dollars or less, according to Gambling Insider.

The study covered 28,845 congressional markets across Kalshi, Polymarket and Polymarket US. For prediction-market readers, the findings raise questions about how much trading capital sits behind displayed prices.

Small sums, measurable price changes

According to Gambling Insider, ACDC also found that 66 percent of markets with live order books could be moved five cents for under 100 dollars. That puts the reported cost of a measurable price change below a modest threshold for a substantial majority of those markets.

The findings concern the cost of shifting prices, rather than evidence that those shifts actually occurred. The supplied summary does not establish how long any price change would persist.

Congressional volume becomes more concentrated

The research also found that the top 1 percent of Polymarket wallets now account for 75 percent of congressional trading volume, compared with 68 percent in August, according to Gambling Insider.

That concentration measure is specific to Polymarket wallets. It is distinct from the price-shifting analysis spanning all three platforms and does not establish how many individual traders control those wallets.

What it means for prediction markets

• Price moves need context: Low reported costs of moving prices suggest that a five-cent change need not reflect a broad shift in trader expectations.
• Volume is unevenly distributed: The rise from 68 percent to 75 percent shows congressional trading volume becoming more concentrated among the top 1 percent of Polymarket wallets.
• Capacity is not proof of conduct: The reported ability to shift prices does not, by itself, demonstrate manipulation or show that any resulting change would last.