Tech and AI stocks have lifted the stock market to record highs. Michael Nagle/Bloomberg/Getty Images New York —

Enthusiasm about artificial intelligence has propelled markets to record highs this year. But the fierce ascent has also raised concerns about a bubble.

AI has been the dominant theme in markets since 2022, when OpenAI first launched ChatGPT. Optimism has since spread among investors about a potential transformative AI boom, and enormous amounts of money have flowed into tech stocks. Valuations have risen to historically expensive levels .

To some analysts, those are red flags that the market might be in a bubble — when investors bid up stock prices beyond what they’re worth, creating an unsustainable rally that often results in a significant downturn, as seen duri

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