Stocks Fall on Fog of War and Fear of AI: Stock Market Today
As the war in the Middle East between the U.S. and Iran continues to drag on stocks and sentiment, a rogue OpenAI model attacks the United Nations.
Stocks opened lower and stayed down on Monday after renewed hope for peace in the Middle East was extinguished when President Donald Trump rejected a proposal from Iran that would have reopened the Strait of Hormuz.
Crude oil closed off its intraday highs after Saudi Arabia said it reopened a crucial pipeline. But bond yields surged again, as markets continue to focus on inflation and interest rates, on top of attacks by OpenAI models.
The front-month West Texas Intermediate crude oil futures contract was up 0.8% to $93.16 per barrel after Trump said the proposal from the Islamic Republic "would not be acceptable." According to Trump, "They want to make a deal where they open the strait immediately because they're losing so badly."
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The 2-year Treasury yield, a proxy for the direction of monetary policy, surged 6.7 basis points to 4.931%, hitting a 52-week high in the process. The 10-year Treasury yield (+5.3 bps, 5.234%) and the 30-year Treasury yield (+4.9 bps, 5.551%) climbed to fresh 52-week highs again on Monday.
"Stocks are still seeking a path out of their latest consolidation," E*Trade from Morgan Stanley Managing Director Chris Larkin says of recent price action, with all three main equity indexes hovering just below all-time highs, despite geopolitical uncertainty. "Tech strength has been doing a lot of the heavy lifting for bulls lately, but the broader market hasn't been able to gain much traction because of rising yields and oil prices."
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At the closing bell, the blue-chip Dow Jones Industrial Average was down 0.7% to 51,481. Papa Dow ended a three-week losing streak on Friday, but the index remains on track for its worst September since 2022. The broad-based S&P 500 shed 0.8% to 7,683, and the tech-heavy Nasdaq Composite was down 0.9% to 26,820.
As Larkin concludes, "With the Fed focused on the inflation side of its mandate, unless this week's labor market data is a major surprise, it will likely play second fiddle to interest rates and energy."
Nvidia announces the biggest stock buyback ever
In addition to announcing a $150 billion expansion to its stock buyback plan, Nvidia (NVDA, +1.7%) introduced new software designed to protect against rogue artificial intelligence (AI) agents.
As Nvidia noted in its press release, "This marks the largest share repurchase authorization increase in history." The increase raises the total on Nvidia's existing repurchase authorization to $235 billion.
Nvidia said it expects to complete its existing stock buyback plan through its fiscal year 2028, which begins on February 1, 2027, and ends on January 31, 2028. CEO Jensen Huang said "a once-in-a-generation platform shift to AI and accelerated computing" supports the move.
"Our cash generation gives us the capacity to invest in the technologies that advance this transformation and return capital to shareholders," the leader of the AI revolution explained in a statement. "This authorization reflects our confidence in the long-term opportunity ahead."
Before the buyback announcement, Nvidia rolled out new tools to strengthen AI security. According to Nvidia, its Open Agent Safety Platform provides "full-stack governance and control" across software and hardware that run AI agents.
"AI's extraordinary potential for society will only be realized if we solve AI safety," Huang said.
"From what we know," Nvidia Vice President of Enterprise AI Justin Boitano said of a recent attack by an OpenAI model on Hugging Face, "this new security platform could have stopped the breach."
Indeed, other semiconductor stocks such as Intel (INTC, -5.7%), Marvell Technology (MRVL, -3.8%) and Qualcomm (QCOM, -7.2%) sold off on Monday in the aftermath of a report that an OpenAI agent used "brute force" techniques to access a website operated by the United Nations.
Bloom Energy (BE, -9.0%), which provides on-site power generation for AI data centers, was the worst-performing S&P 500 stock on Monday.
MongoDB CEO takes job with Meta Platforms
Until Monday morning, MongoDB (MDB, -18.5%) was getting ready to host an "investor day" teleconference on Tuesday for an in-depth look at its long-term strategy to exploit opportunities in the AI boom.
Now, the tech stock is looking for a new CEO, too, after Chirantan Desai stepped down, effective immediately, to take a senior role at Meta Platforms (META, -4.8%).
MongoDB named Dev Ittycheria as interim president and CEO, also effective immediately. Ittycheria was president and CEO of MongoDB from 2014 to 2025, as the company grew its annual revenue from about $35 million to more than $2.3 billion.
MongoDB said it "remains confident in the outlook for the business" and reaffirmed fiscal third-quarter full-year 2027 guidance management shared on September 1.
Mark Zuckerberg said in a statement that Desai will join Meta as chief enterprise platform officer and will lead the next pillar in his empire, reporting directly to the CEO.
According to Zuckerberg, Meta Enterprise Platform will "help businesses use AI to grow and transform in new ways as well."
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