US private equity group Thoma Bravo agrees to buy British cybersecurity company Sophos for £3.1B
US private equity group Thoma Bravo has agreed a $3.9bn deal to buy the cyber security company Sophos, removing another British technology stalwart from the public markets.
Context & Ripple Effects
Sophos returned to public markets only four years ago, raising $125M in a UK IPO that valued it at $1.6B; Thoma Bravo's £3.1B ($3.9B) offer more than doubles that valuation and ends the run. The deal removes one of the last large British security names from the London market and hands it to a US buyer with a specific playbook.
That playbook is already visible in the surrounding coverage: Thoma Bravo went on to take SaaS security vendor Proofpoint private for $12.3B in 2021, agreed to buy UK-listed Darktrace in 2024, and sold Imperva to Thales in 2023 — showing the firm both accumulates and recycles security assets. Sophos is the earliest and, in hindsight, foundational piece of that sequence.
First-order effects
- Sophos shareholders, who bought into the 2015 float at a $1.6B valuation, are cashed out at $3.9B, and the company leaves the London market under US private equity ownership.
Second-order effects
- The take-private becomes a template Thoma Bravo repeats across the sector — Proofpoint in 2021 and Darktrace in 2024 — while Sophos itself later turns acquirer, moving to buy Secureworks from Dell for ~$859M as a PE-owned consolidator.
- Thales's $3.6B purchase of Imperva from Thoma Bravo in 2023 shows the exit side of the same machine: security assets bought private can be resold to strategics once repositioned.
Third-order effects
- If the pattern holds, UK public markets keep ceding their security champions to US private capital, and consolidation shifts to privately held platforms like Sophos buying smaller vendors — a structure where dealmaking replaces public-market scrutiny as the sector's main governance force.
The trend: US private equity, led by Thoma Bravo, is systematically taking cybersecurity vendors private and consolidating them into platforms that then acquire further assets.