If OpenAI LLC were a listed company, Monday would have been a very bad day for the stock. But Chief Executive Sam Altman also happens to be chairman of another, less well-known company that is listed, a developer of nuclear small modular reactors, or SMRs, called Oklo Inc. Monday was a very bad day for that stock.

Oklo's stock price

Source: Bloomberg

Even if the market’s knee-jerk reactions often lend themselves to overinterpretation, Oklo’s 26% sell-off on news of a Chinese competitor to chatbots such as ChatGPT is a useful reminder of nuclear power’s big vulnerability.

The DeepSeek deluge that overwhelmed technology stocks also washed through a number of electricity generator stocks, and for similar reasons. The race to lead in artificial intelligence had spawned a bull case about infinite demand for Nvidia Corp.’s chips that has extended to the electricity required to power those chips. Constellation Energy Corp., with its fleet of nuclear power plants, is the poster child for this burst of enthusiasm, with its meteoric rise over the past year fueled partly by rising profits but mostly by bubbling optimism:........

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