While it seems like bad news, remember that even the CEO can sell shares for many reasons.Rivian Automotive (RIVN -0.10%) arguably exited 2023 with more momentum than any electric vehicle (EV) start-up. The company's stock surged 40% this past December on investors' high hopes -- only then to drop 53% so far this year. To say it's been a bit of a roller-coaster ride for Rivian and other EV makers would be an understatement.More recently, Rivian CEO RJ Scaringe made a move that could give some investors paus ...