Key Highlights

● Fortinet tumbled to about $168.62 and CrowdStrike fell sharply as selling built late.

● One market recap tied part of the slide to a Palo Alto Networks vulnerability disclosure.

● Security stocks fell as sentiment toward AI-exposed growth names soured.

● Varonis rose to around $48.63 after Proofpoint agreed to buy it for $49.75 a share.

A late-session slide

Cybersecurity stocks were not spared as Friday's selling built through the afternoon. The S&P 500 suffered its steepest losses in the final hour of trading, and security software names were among those that accelerated lower into the close.

Fortinet (NASDAQ:FTNT) tumbled to about $168.62 late in the day. CrowdStrike (NASDAQ:CRWD) fell sharply in the late going, and Palo Alto Networks (NASDAQ:PANW) was among the hardest-hit names, according to market reports. Zscaler (NASDAQ:ZS) slid, while Okta (NASDAQ:OKTA) sank to $186.72. Okta is still up sharply for the year despite the drop.

The selling extended to smaller names. SentinelOne (NYSE:S) fell to $21.21, and the stock had slipped three days earlier after announcing a $1.25 billion private placement of convertible notes due 2031. Qualys (NASDAQ:QLYS) and Commvault (NASDAQ:CVLT) fell as well, moving with the sector.

The vulnerability headline

One market recap tied part of the late selling in Fortinet and CrowdStrike to a vulnerability disclosure involving Palo Alto Networks. The recap did not offer details beyond that, and no company was reported to have commented on the matter. Vulnerability disclosures are a routine part of the security industry, as vendors and researchers publish details of flaws so customers can patch them.

The bigger backdrop

The broader story was a sweeping retreat in software and AI-linked stocks. In a 45-stock software basket, 41 names fell, erasing roughly $130 billion in value. The Nasdaq Composite sank 572.99 points to 26,140.03, its worst week since the week ended June 26. The S&P 500 fell 84.62 points to 7,659.44, ending a streak of 55 sessions without a sizable daily drop, the longest such run in over six years, according to market data.

Market commentary described a market that has moved from asking what AI can do to asking how it will be financed. One market commentator said, "The AI group is now splitting between companies that can fund the buildout themselves and those that have to borrow."

Security software companies have positioned themselves as beneficiaries of AI adoption, since more data and more automated systems create more to protect. That made the group vulnerable when sentiment toward AI-exposed growth stocks soured. A senior software analyst at BofA Securities, speaking about CoreWeave (NASDAQ:CRWV) rather than the security group, said: "First of all, this is more sentiment driven. This is not about fundamentals."

One bright spot

Varonis Systems (NASDAQ:VRNS) moved the other way. Proofpoint agreed to buy the data-security company for $49.75 a share in cash, a deal valued at about $6.3 billion. The stock rose to around $48.63. Thoma Bravo is providing equity and debt financing, with an investment from Ontario Teachers', and the deal is expected to close in the first half of 2027. Several brokers, including DA Davidson, Needham and Wells Fargo, moved their ratings to neutral-equivalent levels after the announcement.

Security Names Await Meta and IBM Reads

The next tests come from earnings and the Federal Reserve. The Fed announces its next rate decision on Oct 28. Big tech results begin next week, with Meta (NASDAQ:META), Tesla (NASDAQ:TSLA), IBM (NYSE:IBM) and SAP (NYSE:SAP) due Oct 21, offering a read on enterprise technology budgets. The 10-year Treasury yield, which ended Friday near 5.1, remains a key input for growth-stock valuations.