SE Palmeiras vs Club Cerro Porteño Leads Top Kalshi-Polymarket Arbitrage Gaps

Arbitrage desks monitoring Polymarket and Kalshi have a few wide spreads on the board today, but size execution will be heavily constrained by thin order books. The top spread is in the SE Palmeiras vs. Club Cerro Porteño market, sporting an implied net return of 1,076.47%. Polymarket pricing for Cerro Porteño (YES) is at 7.5¢, while Kalshi is offering Cerro Porteño (NO) at a rock-bottom 1.0¢. Note the operational risk: there is zero reported volume, and the respective expiries are mismatched (Polymarket on May 21 vs. Kalshi on June 4). If executing, watch out for stale pricing and settlement delays on these illiquid books. In political markets, the Florida Governor GOP Primary features a clean 900% theoretical yield with Byron Donalds (NO) at 5.0¢ on Polymarket and (YES) at 5.0¢ on Kalshi. However, this is a duration trap: Polymarket's contract expires in August 2026, while Kalshi's extends to August 2027. Locking up capital for an extra year to capture this spread destroys the annualized capital efficiency. Similarly, GA-04 and the French Presidential run-up present wide margins (594% and 723% respectively) but suffer from massive expiry mismatches and lack of depth. For shorter-duration plays, China's Q2 GDP market offers a 604.23% return with closely aligned July 2026 expiries, but ensure you model the exact strike bounds (Poly's 4.0-4.3% YES vs. Kalshi's Above 4.0% NO) to avoid unhedged exposure in the tail ends of the distribution.