Polymarket US and Kalshi now offer nearly identical taker trading costs, according to a hypothetical scenario published by The Defiant. In the example, executing a 100-contract buy at 40¢ and sale at 60¢ yields a net profit of $16.66 on Polymarket US versus $16.64 on Kalshi after accounting for trading fees. The analysis highlights that even minor price slippage carries meaningful cost implications: a 1¢ worse execution price translates to approximately $1 in additional cost before fees are applied.