FireEye chief executive officer David DeWalt will step down.
He will be replaced by forensics boss Kevin Mandia, the current chief executive officer of FireEye subsidiary Mandiant.
FireEye splurged US$1 billion acquiring the prominent forensics firm in July 2014 and has since bought other well-known security firms including iSight Partners in January for some US$200 million.
The firm's shares dropped some nine percent after it revealed losses increased to US$155.9 million compared to first quarter 2015 losses of US$134 million. ®