Controversial taxi hire app Uber is on the verge of raising $1 billion (£633 million) in a move that could see the firm valued at up to US$40 billion (£25 billion).
The company, which has disrupted London's black cab industry, has attracted US investors T.Rowe Price Group and Fidelity Investments, according to Bloomberg.
Uber was valued at $17 billion (£10.8 billion) in June after it raised $1.2 billion (£750 million) from seven investors.
The latest valuation dwarves those os Twitter, Airbnb and Snapchat, which have market caps of $25.1 billion (£15.9 billion), $13 billion (£8.2 billion) and $12 billion (£7.6 billion) respectively.
Uber has proved controversial in many of the cities it operates in, with licensed taxi drivers claiming the firm is breaking the law because its cabs don't have a regulated meter. The app has also received temporary bans in Germany.
Last week Uber confirmed it was going to investigate one of its New York executives for allegedly tracking a journalist's movements without her knowing.
In a separate incident last week, another Uber executive said the company should create an army of private investigators to track the private lives of journalists who reported on the company.
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