SINGAPORE (Reuters) – SoftBank Group Corp (9984.T) is nearing a deal to invest $1.5 billion in Grab, three times a previously expected $500 million, as Southeast Asia’s biggest ride-hailing firm looks to expand, a person with knowledge of the matter said.

Six-year old Grab has so far raised over $6.5 billion, led by SoftBank, Chinese ride-hailing firm Didi Chuxing and Toyota Motor Corp (7203.T). After a fund raising in August, Grab was valued at around $11 billion.

SoftBank first bought a stake worth $250 million in Grab in 2014 just as Grab began competing with Uber Technologies in Southeast Asia.

Its latest funding in the ride-hailing firm will be made from its Vision Fund, which after raising more than $93 billion last year is the world’s largest private-equity fund.

SoftBank is expected to finalize its investment in Grab this month and an announcement is likely next month, said the source, declining to be identified as the information is not public.

Grab declined to comment, while a SoftBank spokesman did not have an immediate comment.

Reuters reported in October that SoftBank was closing in on a deal to invest about $500 million in Grab, underscoring the tech investment giant’s confidence in the ride-hailing firm’s expansion after it acquired Uber’s Southeast Asian business this year.