Investors are excited about OpenAI’s expansion driving big gains in technology stocks, but a rising number of Wall Street pros fear that the wild pops that add tens of billions of dollars in value in mere minutes are signaling an unhealthy market reminiscent of the dot-com era.

Advanced Micro Devices Inc. took this rocket ride on Monday, as the company’s stock soared, briefly boosting its market capitalization by roughly $100 billion at an intraday high, after the chipmaker signed a deal with OpenAI that could lead to billions of dollars in revenue. AMD’s shares extended gains into a second day, rising as much as 7.5% in early trading on Tuesday. This follows a 36% jump in Oracle Corp. shares last month, which added $255 billion to the software firm’s market value in a single sessi

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