AI-linked stocks tumbled on Monday after the bosses of Anthropic, OpenAI and SpaceX called for a slowdown in “reckless” development citing fears the technology could soon run out of control.

Shares in SoftBank, a Japanese investor that is a big backer of OpenAI, slumped 13%, while the South Korean Kospi stock index, which relies heavily on chip makers that supply AI companies, dropped by 3%.

In Taipei, shares in the big global microchip supplier Taiwan Semiconductor Manufacturing Company dropped 1.2%. Futures for the Nasdaq pointed to a 1.3% drop in the tech-heavy index when the US stock market opens this afternoon.

The sell-off comes after the chief executive of Anthropic, Dario Amodei, appealed for the AI industry to “slow down”.

He said that “building too fast is reckless”, warning that a swarm of AI agents could cause hundreds of billions of dollars of damage by “taking over the entire internet” in future.

Amodei’s claims have been disputed by some experts, but on Monday investors began to price in a slowdown that would make it harder for the industry to pay for hundreds of billions of dollar in investments in AI infrastructure.

The OpenAI CEO, Sam Altman, the Google DeepMind chief, Demis Hassabis, and SpaceX boss, Elon Musk, all posted support for Amodei’s essay on slowing AI development, titled “We Must Pace the Frontier”.

Altman added that he would match Amodei’s commitment to embedding outside evaluators within his company to verify safety practices.

Fears continue to grow over the rapid pace and lack of regulation in AI development. On Monday, a cross-party group of MPs and peers identified a series of human rights risks posed by AI, arguing that no country in the world has laws sufficient to contain them.

However, Donald Trump rejected the calls to pace AI development. The US president told reporters over the weekend: “We’re leading China in AI. We’re the most sophisticated country in the world and frankly, I want to keep it that way because whoever wins AI, wins.”

Jim Reid, of Deutsche Bank, said intense competition in the sector meant it was unlikely AI companies would stop investing so heavily in their technology.

“The competitive race between companies and countries remains intense, and it’s difficult to imagine firms voluntarily stepping back while rivals continue to push ahead.” he said. “It is hard to see China standing still.”

“If leading executives are openly discussing the risks of increasingly powerful systems, it could be them trying to get across how transformative they believe the technology may become and help advertise the power of their product.

“Rather than signalling less spending, it could simply be that a greater share of AI investment is directed towards safety, monitoring and governance alongside the continued build-out of compute infrastructure.”

Amodei’s warning came before reports emerged that Anthropic is on track to be profitable this quarter.

The company told investors that its adjusted operating income would be positive for a second quarter in a row, according to the Financial Times, in a big milestone as it prepares to list on the US stock market this year.

OpenAI has also suggested it will also join the stock market, although Altman said over the weekend that the company would not go public in 2026 due to safety concerns with the technology.