FRANKFURT (Reuters) – Siemens Energy should buy the rest of wind turbine maker Siemens Gamesa to accelerate a turnaround at the Spanish-listed firm, Deka, the second top-10 shareholder in as many weeks to call for the takeover, said on Monday.

The comments from Ingo Speich, head of sustainability and corporate governance at Deka Investment, raise pressure on Siemens Energy’s management, which has so far been unable to improve performance at the 67%-owned unit.

“If Siemens Energy is really serious, there is no way around a full takeover of Siemens Gamesa,” Speich said in remarks prepared for Siemens Energy’s annual general meeting scheduled for Feb. 24.

Refinitiv data shows Deka as Siemens Energy’s ninth-largest investor.

“A full integration would allow Siemens Energy to more easily control, break up structures and streamline decision-making. Look at the low share price as an opportunity to favourably expand your influence and then create value,” Speich said.

Last week, Union Investment also called for the purchase of the 33% Siemens Energy does not own in Siemens Gamesa, a stake that is worth 3.7 billion euros ($4.2 billion).

Speich said trust among investors had been eroded after Siemens Gamesa triggered three profit warnings at its parent company.

“Market trust is destroyed and must be slowly regained,” Speich said.

Sources told Reuters last month that Siemens Energy was stepping up efforts to explore a full integration of Siemens Gamesa.

($1 = 0.8801 euros)

(Reporting by Christoph Steitz; Editing by Miranda Murray and Barbara Lewis)