Why did Rivian stock jump 10% in pre-market today?

Rivian stock surged over 10% pre-market after Uber agreed to invest up to $1.25 billion in the EV maker. As part of the deal, Uber plans to purchase 10,000 autonomous R2 robotaxis, with an option for 40,000 more by 2030. These vehicles will be available exclusively on Uber's platform starting in 2028.