Shares of Tesla dropped on Thursday as Trump responded to Elon Musk's criticism of the budget bill.The stock fell as much as 18%, the most in four years, as the president and the Tesla CEO traded barbs.

Electric vehicles are expected to take a hit under the existing reconciliation budget proposal, but that isn’t the only provision that would seemingly hurt Elon Musk and his business if passed as written.

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.