Fidelis Cybersecurity is a cybersecurity company focused on threat detection, hunting, and targeted response of advanced threats and data breaches. Among its customers includes IBM, the United States Army and the United States Department of Commerce.^[1]

Fidelis offers network security appliances, which include the company's patented^[2] Deep Session Inspection architecture and network traffic inspection.^[3]

In August 2012, General Dynamics announced an agreement to acquire Fidelis into its Advanced Information Systems division.^[4]

In April 2015, Marlin Equity Partners entered into an agreement with General Dynamics to acquire Fidelis Cybersecurity Solutions with the intention of creating a new advanced threat defense service.^[5]

In May 2015, the Wall Street Journal reported that Fidelis acquired Resolution1, an incident response and endpoint detection and response provider.^[6]

In February 2016, the New York Times reported that Fidelis had been hired to provide the hardware and software to monitor the University of California network.^[7]

After acquiring deception technology vendor TopSpin, Fidelis launched its Deception product in January 2018.^[8]

Skyview Capital, a global private investment firm, acquired Fidelis in December 2019.^[9]

In August 2023, Partner One completed the acquisition of all Fidelis customer, distributor and reseller contracts, all intellectual property, equipment, inventory and all other assets required to service these contracts. These assets were acquired as a matter of law under a Uniform Commercial Code Public Sale, and owned by Fidelis Security LLC, a wholly-owned subsidiary of Partner One.^{[citation needed]}