After rising 132% year-to-date, it plunged 26% on earnings day: Why couldn't Fortinet, Inc. (FTNT.US)'s "good results" a good stock price?

US cybersecurity giant Fortinet, Inc. (FTNT.US) recently released its financial report for the third quarter of 2026. Driven by a broad recovery in product demand and strong performance in its AI security business, the company's several core metrics significantly exceeded market expectations, and it raised its full-year billings guidance for the third time this year. However, the stock plunged 26% after hours due to valuation overextension, as well as slowing revenue growth and underperformance in the services business segment. **Slowing Revenue Growth + Services Business Missing Expectations Shakes Market Confidence** The financial report shows that Fortinet achieved total revenue of US$2.08 billion in the third quarter, up 20% year-over-year, exceeding the market expectation of US$2.06 billion; of which product revenue reached US$765 million, surging 37% year-over-year, and services revenue was US$1.313 billion, up about 12.7% year-over-year. Billings, which reflect orders in hand, reached US$2.34 billion, climbing 29% year-over-year. It is worth noting that revenue grew 20% year-over-year. Although the absolute value is not low, it has shown signs of slowing compared with previous quarters. TipRanks noted before the earnings release that "recent signals of slowing revenue growth" mean the company needs to go all out on new businesses, otherwise "continued slowing" will weaken operating leverage. In terms of profitability, the company's GAAP operating margin was 34%, further improving from 31.7% in the same period last year; the Non-GAAP operating margin reached 38.2%, above the market expectation of 36.1%. GAAP net income was US$636 million, with diluted earnings per share of US$0.86, up nearly 40% from US$0.62 in the same period last year; Non-GAAP diluted earnings per share were US$0.91, also above US$0.74 in the same period last year and above the market expectation of US$0.86. It is worth mentioning that Fortinet's largest business segmentserviceshad revenue of US$1.17 billion in the quarter, slightly below Wall Street expectations, with year-over-year growth of only 13%. Services revenue is the most stable source of recurring revenue for cybersecurity companies. This segment missing expectations directly shook the market's confidence in the growth "safety cushion." **Strong Cash Flow Performance, Buyback Authorization Increased by Another US$1.2 Billion** Cash flow was another highlight of this earnings report. Third-quarter operating cash flow reached US$946 million, free cash flow was US$865 million, and the free cash flow margin was as high as 41.6%. As of the end of the quarter, the company held US$3.75 billion in cash and cash equivalents, repurchased US$973 million of stock cumulatively in the first nine months, and the board added a new US$1.2 billion buyback authorization, bringing the total remaining authorization to US$2 billion. In addition, the company repaid US$500 million of senior notes during the reporting period, further strengthening its balance sheet. Total deferred revenue was approximately US$7.93 billion, up significantly from approximately US$7.12 billion at the end of 2025, providing high visibility for future revenue. **CEO: Cybersecurity Is the Key Foundation of AI Security** Fortinet founder, Chairman and CEO Ken Xie said in the financial report that the quarter's outstanding results reflect the company's strong execution and broad demand across its product lines. "This strong momentum stems from our continued leadership in the AI era. As AI creates an entirely new attack surface, cybersecurity remains the key foundation of AI security. Leveraging the unified FortiOS operating system and proprietary FortiASIC technology, our unified platform protects critical AI infrastructure while delivering industry-leading performance and significantly lower total cost of ownership." During the reporting period, the company successively launched the FortiGuard Inline AI security service for FortiGate customers and the FortiLink SASE service that does not require a local firewall, and reached deep partnerships with NVIDIA Corporation, Oracle Corporation, and Microsoft Corporation: it was selected as a top-tier OpenShell reference architecture partner for NVIDIA Corporation (in the security AI direction), partnered with Oracle Corporation cloud to protect enterprise AI applications at scale, and was selected for the Microsoft Corporation sovereign partner ecosystem. In addition, the company was named a Leader in the Gartner Magic Quadrant for Hybrid Mesh Firewalls for the second consecutive year and ranked highest in the "Ability to Execute" dimension. **Raises Full-Year Guidance** Looking ahead, Fortinet expects fourth-quarter revenue of US$2.155 billion to US$2.245 billion, billings of US$2.775 billion to US$2.925 billion, and Non-GAAP diluted earnings per share of US$0.93 to US$0.95. For the full year, the company raised its 2026 revenue guidance to US$8.125 billion to US$8.215 billion, raised its billings guidance to US$9.568 billion to US$9.718 billion, and expects Non-GAAP diluted earnings per share of US$3.54 to US$3.58. This is the company's third increase to its billings guidance this year, highlighting management's confidence in the sustainability of demand. Overall, this financial report confirms the strong prosperity of the cybersecurity industry under the AI wave: enterprises not only need to "use AI" but also to "protect AI," and Fortinet, with its unified platform strategy combining software and hardware, is occupying a favorable position in this round of structural demand. In short, the market believes that this "good result" had already been priced in advance, or even overpriced, and the signs of slowing growth exposed in the financial report precisely triggered a concentrated correction of high valuations. Before the earnings release, Fortinet's stock had already risen 132% year-to-date in 2026, ranking among the top in the cybersecurity sector. Cantor Fitzgerald analysts clearly pointed out before the earnings release that the combination of "strong beat + raised guidance" had been fully priced in by the market, and at current levels "there is limited room for further valuation expansion." When a financial report that "meets or even slightly exceeds expectations" cannot provide new upside catalysts, earlier profit-taking positions will be concentratedly cashed out.