Barranco Cosano vs Sperle

This market covers the ATP Challenger Genoa 2 qualifying final between Javier Barranco Cosano and John Sperle, listed across Kalshi, Polymarket, and Polymarket US. Each contract resolves to the player who advances from the match, with specific handling for retirements, walkovers, and cancellations that varies slightly by venue. John Sperle is the consensus favourite at 61.5%, but the cross-platform picture is unusually split. Kalshi, which carries the bulk of the roughly $1.1M in volume, prices Sperle at just 63.0% and Barranco Cosano at 39.0% — a competitive matchup. Polymarket, by contrast, has Sperle at 99.9% and Barranco Cosano at 0.1%, while Polymarket US shows 99.0% versus 1.0%. Polymarket also lists an ancillary Yes/No pair sitting at 50/50. The gap between Kalshi's near coin-flip pricing and Polymarket's near-certainty on Sperle is stark — roughly 37 percentage points on the same outcome. Polymarket's liquidity here is thin ($35,505) and Polymarket US shows no volume, which likely explains part of the disconnect, whereas Kalshi's book is deep. The cross-platform takeaway: Sperle is favoured everywhere, but the degree of confidence differs dramatically depending on which venue's order book you read.