Trump has threatened to place a 25 percent tariff on imports from Canada and Mexico, as well as a 10 percent additional tariff on all imports from China. Energy resources from Canada will have a lower 10 percent tariff.

Musk, who last year said “things that inhibit freedom of exchange or distort the market are not good,” became $12 billion poorer Monday.

Elon Musk’s incursion into the federal government is unprecedented. It’s also pretty good news for his companies.

One of the largest U.S. labor unions asked a federal judge on Wednesday to block Elon Musk's government cost-cutting effort from accessing the Department of Labor's systems, which the union warned could give the billionaire sensitive information about investigations into his companies.