Volkswagen Group (VW) has increased its investment in its partnership with Tesla rival Rivian, providing Rivian, which has yet to make a profit, with a much-needed source of funding.

According to BBC News, the two companies say the deal, in which they will share EV technology, is now worth $5.8 billion, up from an initial pledge from VW of $5 billion, announced in June.

Shares in Rivian, one of the top U.S. electric vehicle (EV) makers, jumped more than 9% in after-hours trading following the announcement.

The investment comes ahead of the launch next year of Rivian's R2 model, a sports utility vehicle that is smaller and more affordable than it currently offers. The partnership also means VW will be able to use Rivian's technology in its own range of vehicles.

The first VW models equipped with Rivian technology are expected to be available to customers as early as 2027.