SoftBank Group has agreed to spend more than $10 billion to take over US office-space sharing startup WeWork.

The move will see Softbank double down on an ill-fated investment and pay off WeWork's co-founder Adam Neumann to relinquish control. 

The deal represents a stunning reversal of fortune for WeWork as well as its largest shareholder, SoftBank, which has committed more than $13 billion in equity to a company that is now valued at just $8 billion. 

The bailout comes as SoftBank chief executive Masayoshi Son is seeking to convince investors to participate in the Japanese company's second mammoth Vision Fund, for which he is seeking to raise $108 billion. 

To stem WeWork's bleeding, SoftBank will need to reverse its widening losses and find a way to make it profitable. 

The rescue financing also marks a dramatic fall from grace for Neumann, who as recently as last month was preparing to take WeWork public as chief executive after attaining a $47 billion valuation for it in January. 

While WeWork employees now face the prospect of thousands of layoffs, Adam Neumann has secured a $685m side deal with SoftBank to step down from the board of WeWork's owner, The We Company, according to people familiar with the arrangement. 

Mr Neumann faced margins calls on his personal borrowings against WeWork's private stock as a result of the collapse of the company's valuation. 

SoftBank has agreed to extend to him a $500m loan to repay a credit line from JPMorgan Chase & Co, as well as pay him a $185m fee for a four-year assignment as a consultant to WeWork, one of the sources said.

Neumann had drawn down on $395m on JPMorgan's credit line, another of the sources added. 

Under the terms of the deal with SoftBank, he must use the proceeds of selling his stock to first repay the loan extended to him by SoftBank, according to the source. 

Even though he will give up his board seat, Neumann will get two representatives on WeWork's board, according to one of the sources.

Reuters first reported on Monday that Neumann was negotiating stepping down from the board and would serve as an adviser. 

"The consulting arrangement is mind boggling. It's terrible governance," said Nell Minow, vice chair of shareholder advisory firm ValueEdge Advisors. 

"Why pay the guy who got WeWork into this mess for advice. It's adding insult to injury and a little more injury too," Minow said. 

Nevertheless, some WeWork investors said they supported the deal. 

"Adam is a visionary who has created an impactful company which has transformed the way many people work, live and think. We think he deserved to take some money off the table for his contribution to the company," said All Blue Capital managing partner Matt Novak. 

He declined to say how big his firm's stake in WeWork is. 

SoftBank said will it provide a $5 billion debt package to WeWork, comprising of $1.1 billion in senior secured notes, $2.2 billion in unsecured notes, and a $1.75 billion letter of credit facility.

WeWork picked SoftBank's offer over an alternative $5 billion debt package submitted on Monday by JPMorgan. 

SoftBank said it will also accelerate a previous $1.5 billion equity commitment to WeWork in the form of warrants that are due in April at a new price of $11.60 per share. 

SoftBank added it will launch by the end of the year a tender offer for up to $3 billion to acquire WeWork shares from existing investors and employees at a price of $19.19 per share.

Neumann's ability to tender his shares will be capped at $970m, one of the sources said. He currently owns a little over a fifth of WeWork, and is expected to retain a stake. 

SoftBank said it will own 80% of WeWork following the tender offer, but will not be consolidating the company on its books because it will not hold a majority of voting rights.