How Accurate Were Kalshi and Polymarket at Picking Midterm Winners?A New York Times analysis scores prediction markets like Kalshi and Polymarket against election forecasters using Brier scores across 428 midterm races, finding the markets performed no better than forecasts for most of the race but improved as Election Day neared while polling went stale. In South Carolina, bettors gave Darline Graham roughly a 70 percent chance, but she lost to Annie Andrews by about 4.4 points.