CrowdStrike Holdings (CRWD) was the S&P 500's second-best-performing stock Tuesday afternoon as it and other cybersecurity companies were boosted by news of a cyberattack on Chinese artificial intelligence startup DeepSeek. 

DeepSeek, which torpedoed technology stocks Monday as investors digested its claim that its AI assistant runs on less-advanced chips and at a lower cost than those of U.S. rivals like OpenAI, temporarily restricted new registrations Tuesday following “large-scale malicious attacks” on its services.

The attacks may have lifted investor enthusiasm for the cybersecurity sector, with CrowdStrike shares gaining almost 10% to become the top-performing Nasdaq Composite stock. CloudFlare (NET) shares jumped 10% in afternoon trading, while Zscaler (ZS) gained almost 7%, CyberArk (CYBR) rose more than 4%, and Palo Alto Networks (PANW) added more than 2%.

CrowdStrike Reports Perfect Score in Ransomware Test

Elsewhere, CrowdStrike’s Falcon cybersecurity platform achieved a perfect score in a real-world ransomware test, the company said Tuesday. The platform “stopped all known and unknown threats with no false positives,” earning a top rating from cybersecurity software testing firm SE Labs. 

Analysts at JMP Securities maintained a “market outperform” rating on CrowdStrike, with a price target of $400 in a note Tuesday. That’s below the company’s recent level just below an record intraday high of $410. Visible Alpha's mean price target is around $395.

The firm called CrowdStrike and rival Palo Alto Networks "strong contenders to capitalize on the securing of AI infrastructure and data."

CrowdStrike shares are up some 40% over the past 12 months.