[5][6] Sophos was listed on the London Stock Exchange until it was acquired by Thoma Bravo, an American private equity firm in March 2020.

[8] During the late 1980s and into the 1990s, Sophos primarily developed and sold a range of security technologies in the UK, including encryption tools available for most users (private or business).

[10] In 2011, Utimaco Safeware AG (acquired by Sophos in 2008) was accused of supplying data monitoring and tracking software to partners that have sold to governments such as Syria.

[23] In 2007, Sophos acquired ENDFORCE, a company based in Ohio, United States, which developed and sold security policy compliance and network access control (NAC) software.

[28] In May 2011, Sophos announced the acquisition of Astaro, a privately held provider of network security products, headquartered in Wilmington, Massachusetts, USA and Karlsruhe, Germany.

[33] In February 2017, Sophos acquired Invincea, a software company that provides malware threat detection, prevention, and pre-breach forensic intelligence.

[34][35][36] In October 2024, Sophos agreed to acquire SecureWorks, a publicly-held company majority owned by Dell focused on Extended Detection and Response (XDR), for $859 million; the acquisition was completed in February 2025.