I think Tesla news could be contributing a good amount.
"Some investors may also be reacting to news that came out yesterday that Tesla wants to split its stock again. The EV company last split its stock in August 2020, and since then its share price has more than doubled.
While Tesla potentially splitting its stock doesn't directly have anything to do with Rivian, investors often get excited when there's momentum for another company in the same industry. So interest in Tesla's stock right now could be having a spillover effect for other EV makers like Rivian."