Electric vehicle (EV) maker Rivian (NASDAQ: RIVN) said late Tuesday that it closed a hugely important deal, in which giant Volkswagen (OTC: VWAGY) will invest billions in the California-based upstart.

Rivian and Volkswagen Group have finalized a multibillion-dollar joint venture to develop software, paving the way to let the German auto giant leverage the EV startup’s more technical chops in the coming years. Volkswagen will invest up to $5.8 billion by 2027, about 16% more than when the deal was first announced in June.

Shares of Rivian jumped over 15% after the EV maker announced a $5.8 billion investment from German automaker Volkswagen as part of their joint venture.