Thoma Bravo continues to spend billions scooping up security companies, and today said it made a $3.9 billion offer to acquire Sophos.

The Sophos board of directors plan to unanimously recommend the offer to the security vendor’s shareholders. Additionally, company CEO Kris Hagerman is on board with the purchase, calling it “an exciting milestone in the ongoing journey of Sophos.”

The U.S.-based private equity firm has bought out more than 200 software and technology companies for more than $50 billion over its 40-year history. More recently it has targeted security vendors spending nearly $3 billion in 2018 alone. It acquired Sophos’ competitor Barracuda Networks for $1.6 billion, Veracode from Broadcom for $950 million, and Centrify for a reported $400 million.

Thoma Bravo also approached Symantec last November about acquiring that security software company before Broadcom paid $10.7 billion to acquire it. And the buyout firm reportedly set its sight on McAfee as a potential acquisition, but McAfee is now preparing for an initial public offering that could yield at least $8 billion.

U.K.-based Sophos has made 13 acquisitions in its almost 35-year history including Avid Security, DarkBytes, and Rook Security this year alone. Sophos’ customers include Del Monte Foods, Toshiba, Under Armour, and Ford Motor Company.

“We continue to execute a highly-effective and differentiated strategy, and we see this offer as a compelling validation of Sophos, its position in the industry and its progress,” Hagerman said in a prepared statement.