Elon Musk’s bitter falling-out with President Trump could be costly for Tesla. As long as he is persona non grata in the Trump administration, Mr. Musk, the chief executive of Tesla, will struggle to persuade Republicans not to gut climate policies worth billions of dollars to the electric car and battery company.

Retail investors seem to have spotted an opportunity in the sudden feud between U.S. President Donald Trump and his former ally, Tesla CEO Elon Musk, scooping up shares of the electric car maker as they tumbled on the acrimonious standoff.