SoftBank has provided half the money for a $400 million fund that will allow Abu Dhabi's state investment firm to invest in European start-ups.
The fund will help Mubadala to invest between $5 million and $30 million in individual start-ups, people briefed on the deal told the Financial Times which first reported the news.
Mubadala announced in June that it would create the $400 million fund to invest in European tech companies. It said at the time that SoftBank would participate as a strategic investor but did not disclose the extent to which it would contribute.
The two organizations were already connected, with Mubadala investing $15 billion in SoftBank's Vision Fund in 2017. At the time, Mubadala's CEO Khaldoon Khalifa Al Mubarak said in a press release that the investment would help the firm's strategy as a long-term global investor.
The Vision Fund has a track record of making large scale investments. Earlier this month, it invested $940 million in U.S. tech start-up Nuro and $390 million in British fintech company OakNorth.
The new European venture fund will reportedly be run out of a new London office, expected to open in the spring. Mubadala already has a U.S.-venture fund based in San Francisco.
A spokesperson for SoftBank was not immediately available for comment when contacted by CNBC. Mubadala declined to comment further on the report.