The full story
What happened this week
• 21 Oct: PHP, the code behind about 70% of websites, shipped fixes for two critical flaws nicknamed php2shell. AI helped find them, through OpenAI's Patch the Planet program. Attackers had already started trying them, and the UK's cyber agency told organisations to act immediately. • 23 Oct: security stocks jumped together. CrowdStrike +8.3% Zscaler +7.3% Cloudflare +7.3% Palo Alto Networks +7.2% The S&P 500 fell 0.5% the same day.
A second reason: a survey of security resellers by Evercore ISI said company security budgets look firmer into year-end.
In the picture, one padlock is 1% of a day's gain.
The catch: a one-day jump is the market's reaction, and nobody can prove which reason moved it. These stocks were already up a lot in 2026.
