Constellation Energy stock, which has fluctuated wildly this year in the boom and bust of the AI hype cycle, briefly broke out Tuesday in response to news it signed a 20-year deal to sell power to Meta Platforms.

Facebook parent Meta announced an unprecedented deal with Constellation Energy, the largest American nuclear power plant operator, cementing Meta’s turn to turn to nuclear energy to power its energy intensive, generative artificial intelligence initiatives, and sending Constellation shares surging.

Constellation Energy downgraded to Neutral from Buy at Citi, citing limited near-term upside following the stock’s recent rally and news of its power purchase agreement with Meta.