Thyssenkrupp’s chief executive Martina Merz is stepping aside early, the German industrial giant said Monday, in a surprise announcement that sent the company’s shares into a nosedive.

The CEO, who led a major restructuring of the steel-to-submarines group, requested talks on stepping down and the supervisory board agreed, Thyssenkrupp said in a statement.

Miguel Angel Lopez Borrego, CEO of German engineering group Norma, has been put forward to replace her, starting in June.

No reason was given for the departure of Merz — who had been in post since 2019, and was one of the few women bosses at a major German-listed group.

Thyssenkrupp’s shares dropped 12 percent on the Frankfurt Stock Exchange following the news.

Merz had “taken over a very difficult task at a challenging time and since then has initiated a fundamental change process at Thyssenkrupp with great commitment and expertise,” Siegfried Russwurm, chairman of the supervisory board said.

The CEO, whose contract was supposed to run until 2028, had led a complex restructuring of the sprawling conglomerate, which was battling financial problems and a crisis over its future direction.

Merz oversaw the successful sale of the company’s elevator business, earning the group more than 15 billion euros ($16.5 billion).

Costs were reduced and some 11,000 jobs were axed. Thyssenkrupp’s finances gradually improved and it recorded a net profit in the 2021-22 financial year.

But the group had failed to find a buyer for its core steel business, and Merz had faced mounting criticism of her leadership in recent months.

© Agence France-Presse