NBA names Kalshi and Polymarket 'preferred' betting platforms

• —NBA named Kalshi and Polymarket 'preferred' platforms; NHL and MLB struck similar deals earlier
• —Polymarket posted the best price on 99 of 104 bets, with a 1.0% median margin vs 4.5% at sportsbooks
• —Kalshi lists a 1.0% margin, but its 7% taker fee raises the real cut to 4.3%
• —Polymarket paid 4.8% more on underdogs and 2.7% more on favorites than the big five books