Shares in semiconductor designer Nvidia, the world’s most valuable company, fell 3.3% by the close of trading in New York, while Advanced Micro Devices (AMD) dropped 4% and Micron Technology and Sandisk each fell 5%.

The tech-heavy Nasdaq index fund declined 0.5% by the end of the day.

The sell-off followed an appeal by Anthropic chief executive Dario Amodei over the weekend for the AI industry to “slow down”.

However, US President Donald Trump dismissed calls for greater controls on AI as a “sick conspiracy”.

In a social media post on Monday, the US president wrote: “The only control or ‘guardrails’ that AI needs is a STRONG AND SMART (High IQ!) PRESIDENT, and the USA has that, in spades!”

Trump added that his administration had “stopped AI ‘people’ from doing bad, or potentially bad, ‘things,’ like Dario (Anthropic!)”.

“There is a SICK conspiracy going on against AI and Data Centers, and the only one that is happy about it is China. WHOEVER WINS AI, WINS!”, he wrote.

Trump made a similar assessment when he called Nvidia chief Jensen Huang while Huang was on stage at an AI conference in California on Monday.

“It’s a hoax,” Trump said via speaker phone to the audience. “The robots are not going to be taking over the world. That’s not going to happen.”

Meanwhile, the UN security council is planning to hold a meeting on AI next week as international concern over the technology grows, Agence France-Presse reported on Monday.

Shares in SoftBank, a Japanese investor and major backer of OpenAI, fell 13%, while South Korea’s Kospi stock index, which is heavily weighted toward chipmakers supplying AI companies, dropped 3%.

Shares in Taiwan Semiconductor Manufacturing Company, a major global microchip supplier, fell 1.2%.

In Europe, shares in Dutch technology manufacturer ASML, Europe’s biggest company by value and a major semiconductor industry supplier, fell 6%.

However, shares in companies threatened by the rise of AI rallied.

Advertising group WPP rose 5% in London, while analytics company Relx also gained 5%.

Relx had suffered a sharp fall earlier this year after Anthropic launched a suite of new data and automation tools.

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

Some experts have disputed his claims, but investors on Monday began to price in a potential slowdown that could make it harder for the industry to finance hundreds of billions of dollars in AI infrastructure investment.

The OpenAI CEO, Sam Altman, 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 also said he would match Amodei’s commitment to embedding outside evaluators within his company to verify safety practices.

And Jack Clark, an Anthropic co-founder, told the BBC that an AI “kill switch” that could be triggered by a third party may be necessary to prevent catastrophe.

Fears continue to grow over the rapid pace of AI development and the lack of regulation surrounding the technology.

On Monday, a cross-party group of UK MPs and peers identified a series of human rights risks posed by AI, arguing that no country in the world had laws sufficient to contain them.

Meanwhile, China’s top intelligence official warned that the use of AI by adversaries could pose a risk to the country’s political and social security.

Chen Yixin wrote in a government outlet on Sunday that advanced US models such as Anthropic’s Mythos and OpenAI’s GPT-5.5-Cyber could pose serious risks to Beijing’s critical information infrastructure, and called for a comprehensive strengthening of AI security.

Despite concerns over AI risks, Jim Reid of Deutsche Bank said intense competition in the sector meant AI companies were unlikely to stop investing heavily in the 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 signaling 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 that Anthropic was on track to become profitable this quarter.

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

OpenAI has also suggested it could join the stock market, although Altman said over the weekend that the company would not go public in 2026 because of safety concerns surrounding the technology.