LONDON (Reuters) - British cyber-security firm Darktrace said its CEO Poppy Gustafsson would step down on Friday and be succeeded by its chief operating officer Jill Popelka ahead of the completion of its acquisition by U.S. private equity firm Thoma Bravo.

Gustafsson co-founded Darktrace in 2013 and led the company through its listing in London eight years later.

The company, which uses artificial intelligence to detect threats within its customers' networks, agreed a $5.3 billion takeover by Thoma Bravo in April.

Darktrace was backed by Mike Lynch, the British entrepreneur who died last month when his yacht sank off the coast of Sicily.

(Reporting by Radhika Anilkumar in Bengaluru and Paul Sandle in London; Editing by Nivedita Bhattacharjee and Sarah Young)