Tesla stock soared after the election as investors seemed to believe that Musk's close relationship with Donald Trump would benefit his EV company.

Tesla shares dropped more than 15% on Monday, making it the worst performer in the S&P 500 Index. Tesla’s stock has dropped by nearly half in three months. Even so, investors are still debating whether Elon Musk’s electric-vehicle maker remains overpriced.

The delay in producing autonomous vehicles and a threat to federal regulations partly explain the stock's fall, some experts say.