Rivian shares surged as much as 10 percent Thursday after the company announced a robotaxi agreement with Uber. Under the terms, Uber will invest up to $1.25 billion in Rivian in exchange for 10,000 fully autonomous R2 SUVs beginning in 2028, with an option to expand the fleet to 40,000 additional vehicles starting in 2030. The deal adds Rivian to Uber's growing roster of autonomous vehicle partners, which already includes Waymo, BYD, and Lucid.