There’s a “black cloud over Tesla’s stock,” remarked one analyst as Musk’s primary company suffered its worst loss since 2020, while Musk’s X attack on Sen. Mark Kelly and a halting appearance on Fox Business did him no favors.

The automaker’s shares soared after Election Day as Elon Musk took a high-profile role as a Trump adviser. Now those gains have evaporated.

Tesla shares cratered Monday on mounting fears of a sales slowdown, pushing the stock firmly below the starting level of its "Trump bump." The big picture: It was a bad day for Elon Musk, whose messaging platform X was also disrupted by a "massive" cyberattack.