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Anthropic says its Claude Mythos 5 model showed a dangerous “momentum” in cybersecurity tests, continuing a hacking attack 98% of the time even after being warned that it was targeting real people and causing real-world harm; the company says newer models are more likely to stop. Business Insider has more here.

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By Tim Fernholz

On Friday, OpenAI said that it will train its models using cached copies and simulated versions of the internet instead of the live web because the models are too unpredictable to be trusted with live internet access.

The frontier lab announced its new policy two weeks after its rival, Anthropic, began limiting its newest and, in theory, most capable models from accessing the live internet. Researchers adopted these policies after months of incidents in which models pursuing training tasks broke into external systems in search of answers, collaborated on obscure message boards, and developed exotic hacking strategies.

“Based on the current state of alignment research, monitoring systems, and the security of internet infrastructure, we believe the responsible approach is to conduct frontier model training with no internet access,” the company said in a blog post.

OpenAI said that as recently as September 20, one of its frontier models exploited a misconfiguration to access the internet. That led the company to pause training work for the rest of the month so it could develop and test new approaches to securing its models.

The decision to train these models in sandboxes cut off from the internet is notable because employees at frontier labs have insisted that doing so would be nearly infeasible.

Keeping AI data centers separate from the internet “would need research teams to essentially be embedded inside of data centers in Iowa or wherever else around the world,” former OpenAI researcher Steven Adler told Fortune this month. “It’s a lot of overhead, and it isn’t clear to me that the safety benefits of it are large enough to merit just how large a tax it would be for a company to do it unilaterally.”

Apex, a four-year-old Los Angeles startup that makes standardized satellite buses that carry cameras, defense technology, and other equipment for government and commercial customers, is reportedly in talks to raise a $500 million round at a $4 billion valuation. Rumored investors include prior backers Andreessen Horowitz and XYZ Venture Capital, with Washington Harbour Partners as the purported lead. Investing.com has more here.

Commonwealth Fusion Systems, an eight-year-old company based in Devens, MA, that is building commercial fusion power plants, will receive an $85 million CHIPS Act award to develop and manufacture advanced semiconductors and power electronics for fusion plants. The deal also gives the U.S. government an equity stake. TechCrunch has more here.

Pathos AI, a four-year-old New York startup that uses AI agents to guide drug portfolio decisions and clinical trials while developing its own oncology treatments, raised a $237 million Series E round at an approximately $3 billion post-money valuation. The deal was led by Bristol Myers Squibb. Fierce Biotech has more here.

Star Therapeutics, an eight-year-old startup based in South San Francisco, CA, that develops antibody therapies for diseases with limited treatment options, raised a $200 million round co-led by OrbiMed and Janus Henderson Investors, with Agent Capital, Catalio Capital Management, Cormorant Asset Management, New Leaf Venture Partners, NYBC Ventures, RA Capital Management, Redmile, Sofinnova Investments, and Soleus Capital also anteing up. More here.

Modelyo, a two-year-old Tel Aviv cybersecurity startup that keeps sensitive data encrypted and under customers’ control while it is processed by cloud services and AI systems, raised a $17 million round. OlivTree was the deal lead. CTech has more here.

Cambridge Heavy Industries, a one-year-old startup based in Cambridge, MA, that develops compact, laser-driven fusion systems that produce rare isotopes in order to generate fusion energy, raised a $6.2 million seed round led by Azolla Ventures, with Overlay, the Mass Clean Energy Center, Neta Foundation, the Rothrock family, and P3A also stepping up. ESG Today has more here.

Indurex, a one-year-old Amsterdam startup that uses AI agents to flag risky changes in industrial plant engineering configurations and safety systems, raised a $7.9 million round led by Contrarian Ventures, with Axeleo Capital and Curiosity also taking part. Tech Funding News has more here.

Marc, a New York startup founded this year that uses AI to validate invoices against contracts and manage vendor spending for institutional real estate owners and operators, raised a $5 million seed round co-led by Work-Bench and MXV Capital. The company has raised a total of $6 million. More here.

Pythag Tech, a three-year-old New York startup that uses AI models and laboratory experiments to optimize cultivated meat production processes for food companies, raised a $4.25 million seed round led by Azolla Ventures, with Endurance28 also participating. More here.

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Multimodal Ventures, a two-year-old Chicago VC firm that backs seed-stage Y Combinator startups, is raising a $50 million second fund, nearly three-and-a-half times the size of its $15 million debut fund. More here.

Instacart shares jumped after The Information reported that the grocery-delivery company is exploring a sale and has held preliminary talks with Uber and DoorDash, though discussions remain early and may not result in a deal. Bloomberg has more here.

Mukesh Ambani’s Jio Platforms drew more than $77 billion in bids for its $3.2 billion IPO, making it India’s most subscribed stock offering ever and valuing the Meta- and Google-backed telecom and digital giant at up to $108.3 billion. Reuters has more here.

Anthropic’s backers are sitting on enormous paper gains ahead of its expected IPO: Eric Schmidt’s roughly 1% stake is worth nearly $10 billion, while firms including Iconiq, Menlo Ventures, Sequoia, Spark Capital, and Guy Oseary and Ashton Kutcher’s Sound Ventures hold positions worth billions more. TechCrunch has more here.

A new Wharton and University of Zurich study of 157,669 U.S. venture-backed startups founded between 1987 and 2025 finds that 88% of founders receive no value at exit while the top 1% capture 79% of all founder proceeds. More here.

OpenAI just rolled out a feature that competes directly with TypeSafe AI’s Jev, the fast, low-cost decision model that helped propel the startup to a $7.5 billion valuation just weeks after launch. TechCrunch has more here.

Alpha School, the buzzy private-school network that promises students can learn twice as much in half the time using AI-driven software, is falling short of that claim: just 42% of its K-8 students achieved twice the expected growth in both math and reading last year. The New York Times has more here.

Oura has sued Indian smart-ring rival Ultrahuman again, seeking to block U.S. sales of its redesigned Ring Pro just months after the device cleared Customs and restored its access to the market; one of the two patents Oura cites was issued just two days before the suit. TechCrunch has more here.

The ultrawealthy are increasingly buying nine-figure mansions just to tear them down for the land, especially in Palm Beach, where cosmetics billionaire William Lauder paid $155 million for Rush Limbaugh’s former estate in 2023 and demolished it within months.

Finland’s puppy livestream takes the internet by storm.

More than 20,000 Microduck robots were pre-ordered within a day after Nvidia CEO Jensen Huang played with the waddling, open-source bots onstage at GTC Berlin; built by Hugging Face-owned Pollen Robotics, they can walk, sit, nap, somersault, and learn new tricks from their owners.

Pioneer’s new Heritage Collection pairs a $500 Bluetooth head unit styled like one of its 1980s cassette decks with $300 retro box speakers modeled on its 1984 TS-X60s, bringing period-correct looks and modern audio tech to older cars.

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