One weekend essay took about a tenth of the year's gain out of memory stocks

Amodei's call for a slowdown was backed by OpenAI chief executive Sam Altman, xAI's Elon Musk and Google DeepMind chief executive Demis Hassabis.

At the New York open on Monday, Nvidia shares fell 3.2 percent and AMD fell 4.7 percent, with Marvell and Hewlett Packard Enterprise also pulling back.

In the US, shares of Intel, Micron and AMD all fell about 5 percent.

CrowdStrike added 15 percent and ServiceNow gained 6 percent, with SAP, RELX and Wolters Kluwer rising similarly in Europe.

Cybersecurity stocks including CrowdStrike and Palo Alto Networks gained, helped by news of a hack targeting fintech company Revolut.

Charu Chanana, chief investment strategist at Saxo, told the Guardian that memory chips look most exposed, because manufacturers are adding supply against strong demand forecasts that a pause could leave stranded.

Shares of Z.AI, developer of the GLM AI series, tumbled as much as 10.5 percent after making a discounted share placement.

Altman told Fortune that OpenAI has delayed its stock market debut until 2027.

US President Donald Trump on Sunday likened AI critics to "very negative forces" bringing up scenarios that would not happen, and said he wanted to make sure the US remains the industry leader.

China's foreign ministry spokesperson Guo Jiakun told a press conference that "fearmongering, confrontation and vicious competition will only disrupt the process of global AI governance which serves no one's interest."

Anthropic researcher Jacob Coxon resigned, saying that the "people building AI earnestly believe that it could kill us all by the end of the decade."

Global AI capex is seen topping $1 trillion in 2026, according to Goldman Sachs.

Brent crude traded near $108 a barrel after Saudi Arabia shut a key pipeline.

Bets on a Federal Reserve rate rise at Wednesday's meeting had spiked to 86 percent after Friday's inflation report.

Takayuki Miyajima, senior economist at Sony Financial Group, said in a note: "Additionally, uncertainty surrounding the situation in the Middle East continues to weigh on sentiment."

Anthropic still plans to list this autumn and has reportedly chosen the Nasdaq.

Cryptopolitan reported that the statements hit as hard as they did because they came not from regulators but from the founders of the labs at the frontier of the AI race, and that markets are pricing in the possibility that the CEOs act on their own advice.

Anthropic released a threat intelligence report on Thursday detailing how several actors had used its Claude AI models for activities ranging from weapons development and cyber operations to surveillance and fraud.

Morningstar strategist Michael Field said Monday's trading "marks a change for markets, with the negative on software, positive on hardware, trade being turned on its head" and that "For software firms that many feared would be disrupted, this means a stay of execution."

Shares of Samsung, SK Hynix, Intel and Micron are among those up 100 percent or more so far this year.

Mark Haefele, chief investment officer of UBS, said: "Stronger safeguards need not imply the end of the AI capex cycle, in our view, with model training continuing, and expanding adoption requiring higher computing capacity."

Michael Burry said in a message on social media that the warnings from Anthropic and OpenAI were "hype and puffery" and "cover for real uncontrollable slowing growth."

Altman warned over the weekend that making AI safer will come with "significant costs."

Ipek Ozkardeskaya, senior analyst at Swissquote, said the commitments made by AI companies remain even if expected compute demand and revenue growth slow, and believes a genuine slowdown will drag in credit risk and hit data-center operators that have taken on debt and their lenders hardest.

T Rowe Price portfolio manager Sebastien Mallet said: "There is little doubt that AI will change the world," and "But that does not necessarily mean every investment being made today will generate an attractive return."

TrendForce said demand pushed production on some TSMC lines to full utilization, and that TSMC's revenue last quarter grew 12 percent sequentially to US$40.2 billion.

A share up 100 percent year to date that then falls 5 percent is up 90 percent, so Monday's decline removed about a tenth of the year's gain.

SoftBank, an OpenAI backer, dropped about 13.2 percent in Tokyo, connected in part to Sam Altman's comments that OpenAI will not go public this year.

Morningstar reported that South Korean memory chip heavyweights SK Hynix and Samsung closed down 4 percent and 6 percent respectively.

The Taipei Times reported that in South Korea SK Hynix slid 5.3 percent and Samsung Electronics fell 3.7 percent.

Memory maker Kioxia Holdings slumped 9.8 percent and Tokyo Electron lost 3.7 percent in the same session.

Kioxia's 9.8 percent fall was about eight times TSMC's 1.2 percent slip on the same day.