Oracle stock led the latest AI selloff after the hyperscaler’s earnings report and spending guidance renewed fears about excessive capital expenditures.

Jeremy Siegel, Wharton professor emeritus and WisdomTree chief economist, told CNBC on Friday that it’s hard to be certain about the current stock market rotation because there have been “so many head fakes in the past.”

“But as I said, this one has more legs in the sense that there are more things that are happening that throw doubt on how fast or how profitable all the AI buildout is going to be,” he added.

In Oracle’s case, recent delays in data center construction may actually end up being a silver lining if it slows expenditures, but there are still more questions than answers about the profitability of AI, Siegel said.

He noted his research has shown that when companies grow spending faster than their income, they ultimately overexpand, hitting profits and stock returns.

“I’m not saying that that’s necessarily going to happen to AI or certainly all the AI, but that narrative has to come in mind,” Siegel warned.

Also on Friday, Bank of America Securities investment strategist Michael Hartnett said markets are frontrunning a “run-it-hot” scenario expected for next year by rotating into a Main Street trade made up of mid- and small-cap stocks, while getting out of a Wall Street trade consisting of mega-cap names.

Eric Teal, chief investment officer for Comerica Wealth Management, had a similar view in a note on Thursday, saying that the market was dominated by momentum and AI stocks during the first eight months of the year.

But since then, concerns about valuations, margin sustainability, and high debt shifted sentiment around the technology sector.

Financial and healthcare stocks have been more appealing, while small caps and even “micro-cap stocks” will benefit from falling short-term rates, he added.

“More importantly, we foresee this rotation in the early stages with relative valuations remaining attractive,” Teal predicted.