Shares of Tenable Holdings (NASDAQ: TENB), a cybersecurity company, were falling hard this morning after a leaked Anthropic blog post claimed that a yet-to-be-released Claude model has advanced capabilities that could surpass current cybersecurity capabilities.

That is, of course, a bit unsettling for any company trying to protect data, but it's especially worrying for Tenable and other cybersecurity stocks. Tenable stock plunged on the news and is down 8.5% as of 11:31 a.m. ET.

Will AI create the world's first trillionaire? Our team just released a report on the one little-known company, called an "Indispensable Monopoly" providing the critical technology Nvidia and Intel both need. Continue »

A Fortune article broke the news that Anthropic accidentally revealed details about its next in-development AI model, reportedly called Claude Mythos. In an unpublished Anthropic blog post discovered by Fortune, the AI company says that Mythos could pose serious cybersecurity risks.

The blog discussed a new tier of AI models called Capybara that score higher on tests of cybersecurity and coding, making it the company's most advanced model to date.

Of particular importance to Tenable investors is the fact that Anthroic believes the new model could pose serious security threats and said in the draft post that it's "currently far ahead of any other AI model in cyber capabilities" and can "exploit vulnerabilities in ways that far outpace the efforts of defenders."

Anthropic is reportedly giving some cybersecurity companies early access to the new AI model so they can prepare for it.

There's been a lot of hand-wringing among investors lately over cybersecurity stocks and whether AI will be a major disruptor of their businesses. I think there's an argument to be made that Tenable and other cybersecurity companies offer specialized solutions that companies will continue to need in the AI age, and potentially even more so as AI models become more advanced.

But it's also clear that advanced AI models, including a newer version of Claude, could make it harder for cybersecurity companies to keep pace with threats. As such, Tenable shareholders shouldn't panic sell, but should keep a close eye on this space as it evolves.

Before you buy stock in Tenable, consider this:

The Motley Fool Stock Advisor analyst team just identified what they believe are the 10 best stocks for investors to buy now… and Tenable wasn’t one of them. The 10 stocks that made the cut could produce monster returns in the coming years.

Consider when Netflix made this list on December 17, 2004... if you invested $1,000 at the time of our recommendation, you’d have $503,268!* Or when Nvidia made this list on April 15, 2005... if you invested $1,000 at the time of our recommendation, you’d have $1,049,793!*

Now, it’s worth noting Stock Advisor’s total average return is 898% — a market-crushing outperformance compared to 182% for the S&P 500. Don't miss the latest top 10 list, available with Stock Advisor, and join an investing community built by individual investors for individual investors.

See the 10 stocks »

*Stock Advisor returns as of March 27, 2026.

Chris Neiger has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.

Why Tenable Stock Is Falling Fast Today was originally published by The Motley Fool