Darktrace CEO and co-founder Poppy Gustafsson has stepped down with immediate effect and will be replaced by the company’s chief operating officer as the company enters the final stages of a multi-billion takeover.

The British cybersecurity firm, which is the subject of a $5.3 billion acquisition by U.S. private equity giant Thoma Bravo, announced that COO Jill Popelka will take the reins at Darktrace starting today.

"Darktrace has been a huge part of my life and my identity for over a decade and I am immensely proud of everything we have achieved in that time,” Gustafsson said in a statement.

The timing of Darktrace’s announcement, made on a Friday, and the immediacy of the change, will cause speculation about the machinations behind the scenes at the British cybersecurity darling.

Popelka only joined Darktrace as a non-executive director in January before taking on the role of COO in May following the Thoma Bravo announcement. She previously worked at Snap Inc, Accenture, and SAP SuccessFactors.

Popelka’s role as Darktrace COO was the same as that occupied by Stephen Chamberlain, a co-defendant alongside Mike Lynch in a criminal fraud trial in the U.S. over HP’s 2011 acquisition of Autonomy. Chamberlain died in August after being hit by a car while running in Cambridgeshire.

“We are fully supportive of Poppy and the Board's succession plan. Jill is the perfect leader to build on Poppy's tremendous legacy at Darktrace as it embarks on this next phase of its life given her immense experience of scaling and maturing fast-growing businesses,” said Andrew Almeida, a partner at Thoma Bravo.

“She cares deeply about people, about serving customers and about creating a company with a sense of mission and purpose at its core.”

A representative for Darktrace declined to comment further on the statement.

Gustafsson departs

Gustafsson co-founded Darktrace in 2013 alongside a team of mathematicians, entrepreneurs, and intelligence experts.

She previously worked as a corporate controller at Lynch’s Autonomy before its highly controversial $11.7 billion sale to HP, now HPE.

Lynch was an early backer of Darktrace through his venture capital fund Invoke Capital. He held around 3% of the company when he was killed after the Bayesian yacht he was on sank in the Mediterranean Sea in August.

Darktrace floated on the London Stock Exchange in 2021 during the global tech boom. It soared to a £5.7 billion ($7.5 billion) valuation in September of that year before falling back and hovering at the £2 billion ($2.6 billion) mark for several months.



Darktrace’s links to Lynch and Autonomy proved to be a monkey on the company’s back in its brief time as a public company. The group was targeted by short-sellers last year after U.S. hedge fund Quintessential Capital Management raised concerns about the accuracy of Darktrace’s financial statements.

An independent review of Darktrace's accounts by Ernst & Young found no need for the company to amend its previous financial statements.

In April, Thoma Bravo agreed to acquire Darktrace for £4.3 billion ($5.3 billion).

The deal was seen as a fresh hit to the LSE, which has watched several companies leave in recent months in search of higher valuations in rival stock exchanges or on the private market.

Darktrace disclosed Thursday it was waiting for one foreign regulatory approval as part of the Thoma Bravo acquisition, due September 28, after which it would seek a U.K. court sanction to close the deal.

This story was originally featured on Fortune.com