Elon Musk lost more than $60 billion in wealth following Republican defeats in the US midterm elections, despite spending about $446 million to help the party retain control of Congress.
Much of his political spending went to Texas, where the Republicans suffered a major setback.
Tesla shares fell 5.7%, while SpaceX was reported down 7.6% in early trading, further hurting Musk's fortunes.
A Democratic-controlled Congress could also increase scrutiny of a potential Tesla-SpaceX merger before Trump leaves office in 2029.
Source: FT