Key Highlights

● Fortinet shares closed 20.09% lower on Thursday, October 29, at about $139.10.

● Third-quarter Revenue rose 20% to $2.08 billion and billings grew 29% to $2.34 billion.

● Full-year service revenue is now guided to $5.15 billion to $5.17 billion.

● The board added $1.2 billion to its buyback authorization, leaving $2 billion available.

Fortinet (NASDAQ:FTNT) is in focus heading into Friday's session after one of the worst days in its history. The Cybersecurity company's shares closed 20.09% lower on Thursday, Oct. 29, according to market data, with one market news summary listing the stock at $139.10. The selloff followed third-quarter results released after the close on Wednesday. No reliable pre-market quote for Friday was found, so the direction of early trading is not confirmed.

The aftermath of a 20% plunge

The headline numbers looked strong. Revenue rose 20% to $2.08 billion, product revenue jumped 37% to $765 million and billings grew 29% to $2.34 billion, according to the company's release. Non-GAAP Earnings were $0.91 per share, up from $0.74, and non-GAAP Operating Margin widened to 38.2%.

The problem was the outlook for services, the subscriptions and support contracts that provide recurring revenue. Market reports said Fortinet raised its 2026 sales forecast but cut its forecast for service revenue. The company now guides full-year service revenue to $5.15 billion to $5.17 billion. Service revenue grew about 13% in the third quarter, to $1.31 billion, well behind the pace of product sales.

Why investors care so much about services

Fortinet sells firewalls and other network security hardware, along with security subscriptions and support. Product sales can surge with hardware refresh cycles, but investors value the recurring service stream more because it is more predictable and carries higher margins. A lower service forecast signals that the subscription engine may be slowing, even as hardware sales boom.

Management focused on the opportunity in artificial intelligence. "As AI introduces entirely new attack surfaces, Network Security remains the critical foundation of AI Security," founder, chairman and CEO Ken Xie said in the release. He also said the company was "very pleased with our excellent third quarter results." Investors clearly focused elsewhere, on the mix of growth rather than the total, and on what slower service growth could mean for margins in 2027.

Fortinet guided fourth-quarter revenue to $2.155 billion to $2.245 billion, billings to $2.775 billion to $2.925 billion and non-GAAP EPS to $0.93 to $0.95. For the full year, it expects revenue of $8.125 billion to $8.215 billion and non-GAAP EPS of $3.54 to $3.58. The board also added $1.2 billion to its buyback authorization, leaving $2 billion available.

Sector fallout and what comes next

The drop has rippled through cybersecurity. One market commentator noted that the cybersecurity ETF CIBR's one-month lead over the S&P 500 had narrowed to about 0.5 percentage points after Fortinet's selloff.

As a Nasdaq-100 member, Fortinet's decline also weighs on an index already under pressure. Nasdaq-100 futures were down about 2.6% around 8 a.m. ET on Friday, according to market quotes, after Amazon (NASDAQ:AMZN) and Intel (NASDAQ:INTC) results reignited worries about AI spending.

After a 20% one-day fall, the stock could see further selling or a partial rebound as investors reassess. Key risks include a continued slowdown in subscription growth, tougher competition from rivals selling platform-based security, and the possibility that the product surge reflects a one-time hardware upgrade cycle.

Investors will watch for analyst rating and target changes, any comments from management at upcoming investor conferences, and how quickly the company puts its enlarged buyback to work. The fourth-quarter report, expected early next year, will show whether service growth stabilizes. Until then, the debate will center on whether Thursday's sharp drop already prices in a slower subscription Business or whether expectations still need to come down further, especially if rivals report stronger Recurring Revenue trends.