Nuclear power plays Vistra and Constellation Energy have become two of the top performers on the S&P 500 index this year, sandwiching Nvidia and riding the artificial intelligence energy wave that has propelled utilities. VST leads the S&P 500, up 259% in 2024, while Constellation Energy sits third with a 144% advance this year. Vistra is a diversified electric utility and power generation firm, with natural gas, nuclear, solar and battery storage facilities.