Vistra shares slumped after a deal for its Comanche Peak nuclear plant raised some concerns about its pricing. Robinhood Markets (HOOD) shares surged over 12% to close at an all-time high and secure the top performance in the S&P 500 on Monday. CEO Vlad Tenev shared a social media post showing that the brokerage platform operator surpassed 4 billion event contracts traded on its prediction markets. Piper Sandler analysts had cited prediction markets growth when they boosted their price target on Robinhood's stock last week. Shares of Williams-Sonoma (WSM), parent of numerous home goods brands, sank 4.7%, losing the most of any stock in the S&P 500.