The deal values Uber at $48 billion compared to the last valuation at which Uber raised money which was $68 billion.
It is thought that Softbank will take 15% of the investment with Dragoneer and the other investors picking up an initial 5% but likely to add to their stakes later.
Softbank is a prodigious investor in app-based taxi companies with stakes in the China service Didi Chuxing, the India service Ola and the Brazil service called 99.
Uber has raised around $13 billion. In Q3 it had gross bookings of $9.7 billion, revenue of $2 billion and a loss of $1.46 billion.