Indian oil-to-telecoms conglomerate Reliance Industries Ltd said on Friday that Abu Dhabi state fund Mubadala Investment Co will buy a 1.85% stake in its digital unit, Jio Platforms, for 90.93 billion rupees ($1.21 billion).

Reliance has now sold a combined 19% interest in Jio Platforms, which houses movie, music apps and telecoms venture Jio Infocomm, in six fundraising deals including a 9.99% stake sale to Facebook Inc for $5.7 billion.

The interest in Jio Platforms highlights its potential to become the dominant player in India's digital economy. The telecoms unit has already decimated several rivals with cut-throat pricing and is counting on Reliance's retail network to expand into e-commerce.

The Jio Platforms investment is the largest in an Indian firm by Mubadala, which is the second-biggest state investor in Abu Dhabi after Abu Dhabi Investment Authority (ADIA), managing about $240 billion in assets.

The other recent investors in Jio Platforms are private-equity firms General Atlantic, Silver Lake, Vista Equity Partners, and KKR & Co Inc.

Morgan Stanley served as a financial adviser to Reliance Industries, the company said in a statement.

($1 = 75.4390 Indian rupees)

(Reporting by Ismail Shakil in Bengaluru and Hesham Abdul Khalek in Cairo Editing by Chris Reese and Anil D'Silva) ((Hesham.AbdulKhalek@thomsonreuters.com;))