Olympus Corp announced on Monday that it has agreed to sell its microscope division to private equity firm Bain Capital for 427.6 billion yen ($3.1 billion), the Japanese company’s largest divestiture to date.

The sale of the unit, which also manufactures industrial endoscopes and x-ray analyzers, comes as Olympus accelerates the restructuring of its business portfolio, with the goal of focusing primarily on medical technology.

Bain won over global private equity firms such as Carlyle Group and KKR & Co, people with direct knowledge have said.

In its overhaul, Olympus has invited activist investor ValueAct Capital on to its board, bought several overseas medical equipment firms and sold its digital camera business that had been a longtime money-loser.

Its shares have nearly tripled since it started to re-organise itself early in 2019.