For months, Tesla shareholders were tormented by Elon Musk’s role in the administration of President Donald Trump. But any relief brought by his formal government exit last week quickly turned to fear as the electric-vehicle maker’s chief executive traded barbs with his former boss.

The relationship between Elon Musk and President Donald Trump appears to have entered a new phase of pronounced tension and public disagreement.

Investors fear that the dispute between Elon Musk and President Donald Trump "will stop their friendship and change the regulatory environment for Tesla on the autonomous front over the coming years under the Trump administration,