Solar-power company SunEdison Inc. filed for bankruptcy protection on Thursday, pledging to curb a debt-fueled global expansion that pushed the company’s stock to great heights before fueling its rapid collapse.

The filing caps a dramatic decline for a company that was worth nearly $10 billion last summer, when it nurtured plans to become a global clean-energy giant. SunEdison used a combination of financial engineering and cheap debt to buy up renewable-power projects around the world before the market turned sour last summer and investors soured on its business model.

SunEdison said it would use the bankruptcy process to reduce its borrowings, which stand at more than $16 billion, including the debt of two publicly traded subsidiaries, TerraForm Power Inc. and TerraForm Global Inc. Those subsidiaries—separate entities known as yieldcos that buy operating projects from developer SunEdison and pay out cash flow to their shareholders—didn’t file for bankruptcy and said in statements that they have sufficient liquidity to continue to operate, though much of SunEdison’s value is derived from its controlling stake in them.

SunEdison listed assets of $20.7 billion in court papers.

“Our decision to initiate a court-supervised restructuring was a difficult but important step to address our immediate liquidity issues,” said Chief Executive Ahmad Chatila. “The court process will allow us to right-size our balance sheet and reduce our debt.”