FireEye announced a $400 million investment led by private equity firm Blackstone Group and said it bought security startup Respond Software for $186 million late Thursday. The two deals sent its stock skyrocketing 17% in after-hours trading.

FireEye, which debuted its Mandiant Advantage platform late month, said it will use the funding to support “strategic growth initiatives,” which includes the Respond Software acquisition. It will also use the investment to grow its cloud, platform, and managed services portfolio.

ClearSky, a security-focused investment firm, also participated in the $400 million investment.

In a separate announcement, FireEye said it bought Respond Software for $186 million in cash and stock.

Respond, a 4-year-old company based in Mountain View California, developed a cloud-native extended detection and response (XDR) engine that uses artificial intelligence (AI) to automate security alert investigation. FireEye says it will integrate this engine, called Respond Analyst, into its Mandiant Advantage platform giving it vendor-agnostic XDR and investigation capabilities. It will also use Respond’s technology to boost its managed security services portfolio.

“With Mandiant’s position on the front lines, we know what to look for in an attack, and Respond’s cloud-based machine learning productizes our expertise to deliver faster outcomes and protect more customers,” FireEye CEO Kevin Mandia said in a statement. “This creates a learning system with new capabilities that will enable us to expand our Mandiant portfolio and drive new XDR revenue through our Mandiant Advantage platform.”

Respond will “enhance the total value and awareness of Mandiant,” said BMO Capital’s Keith Bachman in a research note. He added that Respond’s XDR module will likely improve growth rates of FireEye’s security platform and its managed services.