Sebastian Siemiatkowski, the co-founder of Klarna, told the Financial Times that he is worried about the tech world’s race to pour huge sums into massive AI data centers, even though he personally holds stakes in companies driving the same boom.

Sebastian said the rush to build computing hubs at record cost has reached a level that makes him uneasy, and he is questioning whether the spending makes sense.

“I think [OpenAI] can be very successful as a company but at the same time I’m very nervous about the size of these investments in these data centers,” he said. “That’s the particular thing that I am concerned about.”

He spoke from a position that is both involved and exposed.Through his family office Flat Capital, Sebastian owns shares in OpenAI, Perplexity, xAI, and Cerebras.

At the same time, Klarna has become one of the most aggressive adopters of AI in the corporate world, using automated tools to remove more than half of its workforce over the past few years.

The company now lets an AI system handle two‑thirds of customer service interactions, a shift that Sebastian often highlights when discussing how fast the industry is changing.

But the same rise in AI has not helped Klarna’s market value.Since its $15 billion IPO in New York in September, the company’s shares have fallen more than 20 percent.

Klarna will publish its third‑quarter results tomorrow, and Sebastian said he is also thinking about whether he needs to hedge his personal exposure to the companies involved in the huge infrastructure spending wave.

Sebastian questions trillion‑level AI construction bets

Sebastian said the numbers being spent today are far beyond what he thinks is necessary to run advanced AI systems.

He pointed to the combined $112 billion in third‑quarter capital spending announced by Alphabet, Amazon, Meta, and Microsoft, and said he is unsure whether the size of these investments will make sense once the industry stabilizes.

He also noted that OpenAI, which still runs at a loss, has made $1.5 trillion in total commitments to secure future access to computing resources.The scale of that figure is the core of his concern.

Sebastian said the popularity of tools like ChatGPT proves AI demand is global, but added, “[But] that’s a different thing than asking myself ‘is it worth putting a $1tn worth into servers.’ I am concerned that piling that kind of money into data centers may turn out to be not worth it.”

Sebastian argued that future AI models will likely need less power, not more, because they act like what he called the “most effective compression technology ever invented,” and he believes the systems will run more efficiently over time.

He pointed to outside examples as well. In January, Chinese AI group DeepSeek shook the market by unveiling low‑cost, power‑efficient models that compete with U.S. systems at a fraction of the cost.

Investors reacted quickly, and the past month has seen sell‑offs in several U.S. companies tied to the AI build‑out as doubts grew over whether the spending levels make sense.

He said he has raised these concerns privately with the leadership teams of the companies he invests in and suggested the internal mood is much more cautious than public statements imply.

“People have an incentive to say I’m wrong,” said Sebastian. “And I feel, behind doors, people are more concerned about what I’m saying than they are in public.”

He warns that everyday investors are being dragged into the AI bet

Sebastian said the rally in AI names is now so large that index fund flows are pushing pensions into the trend whether people like it or not.

He mentioned Nvidia, now valued at about $4.5 trillion, as an example and said the amount of market wealth tied to AI worries him. “That makes me nervous, because of the amount of wealth that is currently automatically allocated into this trend, without some more thoughtful thinking,” he said.

Sebastian added, “You can say ‘I disagree with the fact that Nvidia is worth that much and I don’t care, some rich people are going to lose some money.’ But the truth is, because of the index funds and how this works, your pension right now is going into that theory that it is a good investment.”

He also noted that well‑known hedge fund manager Michael Burry, famous for predicting the 2008 housing crash, shut down his fund Scion Capital last week after saying the market had lost touch with reality.

Scion had short positions against Nvidia and Palantir. Sebastian said, “I partially agree with Michael Burry. The question again is about timing because he’s betting against the whole market.”

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