Shares of F5 Inc (FFIV) tumbled 6.69% in Monday's trading session following the company's release of its fourth-quarter results and weak forward guidance, largely impacted by a recent cybersecurity breach. Despite reporting strong Q4 earnings that beat analyst expectations, investors focused on the company's cautious outlook for the coming fiscal year.

F5, a leading provider of cybersecurity solutions, disclosed that hackers had gained "long-term, persistent access" to certain company systems, including the source code for one of its key cybersecurity services. This breach, which triggered alarm over potential risks to U.S. and UK government systems, is expected to weigh heavily on the company's near-term performance. CEO François Locoh-Donou stated, "F5 anticipates some near-term disruption to sales cycles as customers focus on assessing and remediating their environments following the recent security incident."

For fiscal year 2026, F5 projected revenue growth of 0% to 4%, significantly below analysts' expectations of 4.8% growth. The company also provided a conservative first-quarter outlook, forecasting revenue between $730 million and $780 million, which falls short of the $791 million consensus estimate. F5 expects the impact of the cybersecurity incident to be more pronounced in the first half of the fiscal year before normalizing in the second half. Additionally, the company warned of potential modest impacts on its operating margins in the near term due to these disruptions. The combination of these factors led to the sharp decline in F5's stock price, as investors reassessed the company's growth prospects in light of these challenges.