Michael M. Santiago / Getty Images High-flying AI stocks tumbled on Friday amid a broad risk-averse pivot on Wall Street. Utilities Constellation Energy Corp. (CEG) and Vistra (VST) each closed about 8% lower, while nuclear energy technology company Oklo (OKLO) slid 9%. Oklo, which is backed by OpenAI CEO Sam Altman, lost nearly 30% of its value this week. Nuclear energy stocks have soared in the past year amid booming demand for electricity to fuel power-hungry artificial intelligence models. Vistra and Constellation were two of the S&P 500’s best-performing stocks last year. Even with today's big losses, they are up...