Private equity giant Thoma Bravo has agreed to purchase email security powerhouse Proofpoint for US$12.3 billion in the biggest cybersecurity acquisition of all time. The Sunnyvale, Calif.-based company said the proposed acquisition will give Proofpoint the flexibility and resources needed to continue providing an effective cybersecurity and compliance offering. Proofpoint also expects to benefit from Thoma Bravo’s operating capabilities, capital support and deep sector experience. The deal is expected to close in the third quarter of 2021. “We believe that as a private company, we can be even more agile with greater flexibility to continue investing in innovation, building on our leadership position and staying ahead of threat actors,” Proofpoint Chairman and CEO Gary Steele said in a statement. “Thoma Bravo is an experienced software investor, providing capital and strategic support to technology organizations, and our partnership will accelerate Proofpoint’s growth and scale at an even faster pace.”