Plus: Meta and YouTube just took a crushing legal blow over tech addiction.
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Fortune 500 Digest with Alyson Shontell
Saturday, March 28, 2026
Foreword
Alyson Shontell
Editor-in-Chief

What is Claude Mythos?

That’s what Fortune’s Beatrice Nolan wondered after she heard a tip about it earlier this month from sources on her AI beat. She exclusively reported its existence for Fortune on Thursday night.

In her reporting, Beatrice discovered that Anthropic had inadvertently placed roughly 3,000 digital assets in an unsecured, publicly searchable database. The documents included a draft blog post that revealed the existence of Mythos, a not-yet-released LLM model in the works from Anthropic. Mythos is gearing up to be Anthropic’s most powerful model yet, the company said in the draft blog post, and it could pose serious cybersecurity risks if it’s not tested and deployed properly.

I asked Beatrice for the story behind her story, and what it means for Anthropic in light of the ongoing Big Tech AI model wars.

How she reported the scoop: “These stories came from reviewing publicly accessible web infrastructure tied to Anthropic’s site, alongside analysis from independent security researchers,” Beatrice says. “Anthropic later confirmed to us that it was indeed testing a new model, which it described as its most capable yet. The company is treating it cautiously, limiting access to a small group of early users because of its potential risks—particularly in cybersecurity.”

What it means for the Big Tech AI wars: “For Anthropic, it signals increased concern about the use of AI tools in more advanced cyberattacks, including state-sponsored operations that could automate the discovery and exploitation of software vulnerabilities at scale,” Beatrice says. “But for competitors, it raises the bar again—especially around coding and security—while also intensifying concerns about how quickly these models could outpace existing safeguards.”

Beatrice’s scoop rattled markets, with cybersecurity stocks falling on fears that more advanced AI could both accelerate attacks and disrupt the sector. And it’s another sign of just how fast things are moving in this disruptive corner of the business world.

Check out her exclusive details on Anthropic’s yet-to-be-released most powerful model yet.

Follow Alyson on X, LinkedIn, TikTok, Instagram, and the Titans and Disruptors vodcast.

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Catch Up

Rankings
Fortune 500 C-suite Power Moves
Insight Enterprises (No. 447) appointed Jack Azagury CEO, effective April 13. Dollar General (No. 112) appointed Jerry W. “JJ” Fleeman Jr. CEO, effective Jan. 1, 2027. Rush Enterprises (No. 479) appointed Jody Pollard COO. Ingredion (No. 498) appointed Jason Payant interim CFO, effective April 1.
And more in this week's Fortune 500 Power Moves.
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Deals & Developments
  • A Los Angeles jury ruled that the "addictive design" of Instagram and Facebook, owned by Meta Platforms (No. 22), and YouTube, owned by Alphabet (No. 7), contributed to serious mental health problems in a 20-year-old plaintiff, awarding her $3 million in damages. The verdict could set a precedent for similar lawsuits and force Silicon Valley to confront platform features designed to keep users scrolling. Read more: At this rehab for addicted teens and adults, tech is treated like heroin
  • Estée Lauder (No. 279) confirmed it is in preliminary talks to acquire Spanish beauty company Puig in a potential deal that would create a beauty giant valued at over $40 billion. The deal, first reported by the Wall Street Journal, would unite brands like Clinique, La Mer, and Jo Malone with Puig’s Charlotte Tilbury, Rabanne, and Jean Paul Gaultier.
  • Corebridge Financial (No. 224) and Equitable Holdings (No. 338) agreed to an all-stock merger, creating a combined life insurance, retirement, and wealth management company worth approximately $22 billion. The new company will retain the Equitable name. Corebridge President and CEO Marc Costantini will assume those same roles, as will Equitable CFO Robin Raju.
  • Sumitomo Mitsui Financial Group (No. 204 on the Fortune Global 500) was reported by the Financial Times on Tuesday to be weighing a takeover bid for Jefferies Financial Group (No. 403). Further reporting by Bloomberg, however, discounted the “rumors,” as an anonymous SMFG spokesperson characterized them. Sumitomo Mitsui Banking Corp, a subsidiary of the Tokyo-based financial services group, already owns a 4.48% stake in Jefferies.
Overheard
“We’ve been working closely…to ensure our power needs are met and, importantly, so that…consumers aren’t paying our costs.”
—Rachel Peterson, Meta’s (No. 22) VP for data centers, in a statement regarding the company’s agreement with Entergy (No. 355) to build and finance several power plants to electrify its Louisiana AI data center complex, Hyperion.
On earnings calls:
  • Chewy (No. 357) met estimates with $3.26 billion in quarterly revenue, up 8.1% year-over-year on an adjusted basis, and projected full-year fiscal 2026 net sales of $13.6 billion to $13.75 billion, topping analyst expectations. CEO Sumit Singh said the company expects pet industry dynamics in 2026 to “largely mirror 2025” with “resilient” demand.
  • Jefferies Financial Group (No. 403)