Siemens Gamesa said on Monday it plans to cut as many as 6,000 jobs worldwide as it braces for sales to plunge by as much as a fifth next year.
The job cut would amount to more than 20 percent of the company's total workforce of around 26,000.
Wind turbine makers have been facing growing competition, putting pressure on pricing and inventory values and raising expectations for more takeovers to build scale.
The Spanish-based wind power joint venture, which cut its earnings forecasts twice in recent months, has to date been planning to cut only 700 positions.
But the company said on Monday it expects sales to fall to between 9 and 9.6 billion euros this year from about 11 billion in fiscal 2017, a 5-percent gain from year-earlier levels.
Underlying EBIT declined almost a fifth to 774 million euros in fiscal 2017 ended Sept. 30, though plunged by nearly two thirds to 192 million euros in the six months since April, it said.
"Our financial performance is still not at the level we're all aiming for," chief executive Markus Tacke said.
Siemens merged its wind division with rival Gamesa this year following deals that saw Germany's Nordex (NDX1.HA)
buy the turbine unit of Spain's Acciona and General Electric take over Alstom Energy of France.
"We believe that the planned restructuring measures at Siemens (SIEMENS.NS)
Gamesa are necessary because the market and regulatory environments are changing structurally," a spokesman for Siemens said.
(Reporting by Andreas Cremer and Alexander Huebner; Editing by Adrian Croft)