WeWork, the New York start-up that helped pioneer the concept of shared office space, has won a $4.4bn (£3.4bn) vote of confidence from two huge investment groups.
SoftBank, the Japanese telecoms and technology giant, is buying a stake worth $3bn in the US firm.
The investment follows a previously announced $1.4bn injection by SoftBank to fund WeWork's Asian expansion.
Some of the investment is being made through its Vision Fund.
The fund is an investment vehicle focused on emerging technology that is also backed by entities that include Apple, Foxconn and Saudi Arabia's sovereign wealth fund.
WeWork has 10 million sq ft of space in 16 countries around the world. It does not own properties, but sub-leases offices to individuals and companies.
Masayoshi Son, chief executive of SoftBank, said: "WeWork is leveraging the latest technologies and its own proprietary data systems to radically transform the way people work."
The companies did not say how much of the investment will come from SoftBank directly, and how much from its Vision Fund,
They also declined to say what stake SoftBank will now hold in WeWork. Two representatives of the Japanese group will join the board.
SoftBank invested $300m in WeWork in March, which was said at the time to be a prelude to a bigger commitment.
The Vision Fund has more than $93bn at its disposal. The fund has also invested in India e-commerce company Flipkart, robotics firm Brain Corp and vertical farming start-up Plenty in California.