(Reuters) -Companies announcing multi-billion dollar investments in artificial intelligence have raised concerns about the formation of a bubble reminiscent of the dotcom boom and bust.

Investors are on guard for signals that demand is tailing off or that the massive spending is not paying off as anticipated.

A BofA Global Research's monthly fund manager survey revealed that 54% of investors said they thought that AI stocks were in a bubble compared with 38% who do not believe that a bubble exists.

Here is a list of industry executives, economists and analysts' takes on the topic:

BANK OF ENGLAND Global markets could tumble if investors' mood sours on the prospects for artificial intelligence, the Bank of England said on October 8.

"The risk of a sharp market correction has increased," the BoE's Financial Policy Committee said in a quarterly update, in its sharpest warning to date of the dangers of an AI-triggered market slump, adding that the risk of spillovers to Britain's financial system from such a shock was "material".

BRYAN YEO, GIC PRIVATE CHIEF INVESTMENT OFFICER "There's a little bit of a hype bubble going on in the early-stage venture space," said Singapore sovereign wealth fund's Yeo during a panel discussion at the Milken Institute Asia Summit 2025 on October 3.

"Any company startup with an AI label will be valued right up there at huge multiples of whatever the small revenue (is),... That might be fair for some companies and probably not for others."

JEFF BEZOS, FOUNDER AND EXECUTIVE CHAIRMAN OF AMAZON "When people get very excited as they are today about artificial intelligence, for example, every experiment gets funded,... And investors have a hard time in the middle of this excitement distinguishing between the good ideas and the bad ideas," Bezos said during the Italian tech week on October 3.

"A bubble like a banking bubble, a crisis in the banking system, that's just bad ... The ones that are industrial are not nearly as bad, it could even be good because when the dust settles and you see who are the winners, society benefits from those inventions."

JOSEPH BRIGGS, ECONOMIST AT GOLDMAN SACHS' ( GS ) GLOBAL ECONOMICS RESEARCH The flood of multibillion-dollar investments pouring into U.S. artificial intelligence infrastructure is sustainable, pushing back on mounting concerns that the sector's spending spree could be overheating, Briggs said in a note on October 16.

While the overall macroeconomic case for AI investment remains strong, he cautioned that "the ultimate AI winners remain less clear," with fast technological change and low switching costs potentially limiting first-mover advantages.

MORTEN WIEROD, ABB CEO"I don't think there is a bubble, but we do see do see some constraints in terms of construction capacity not keeping up with all the new investments," Wierod told Reuters on October 16.

"We are talking about trillions in investment," he said, adding: "That will take a few years to implement because there is not enough people and resources to build all this."

PIERRE-OLIVIER GOURINCHAS, IMF'S CHIEF ECONOMIST The U.S. artificial intelligence investment boom may be followed by a dot-com-style bust, but it is less likely to be a systemic event that would crater the U.S. or global economy, Gourinchas, said on October 14.

"This is not financed by debt, and that means that if there is a market correction, some shareholders, some equity holders, may lose out."

SAM ALTMAN, OPENAI CEO"Are we in a phase where investors as a whole are overexcited about AI? My answer is yes," Altman told tech media The Verge in August.

"Someone is going to lose a phenomenal amount of money. We don't know who, and a lot of people are going to make a phenomenal amount of money." UBS Almost as many investors who feel we're in an AI bubble are also hanging on to their investments in the sector, UBS equity strategists said on October 14.

"Most felt we were in an AI bubble, but that far from the apex of a bubble peak and thus around 90% of the people who said we were in a bubble said they were still invested in many of the AI-related areas."