Elon Musk announced his intention to launch a third party, reigniting his feud with Donald Trump and sending Tesla shares spiraling. Max Chafkin and Mark McKinnon discuss on The 11th Hour.

Mr. Musk’s involvement in politics and his financial support for the president’s campaign was once seen by investors as a benefit to Tesla, fueling a steep rise in company shares after the election last year. That association has now turned into a liability. Tesla shares are down 40 percent from their peak in December.

Tesla shares fell on Monday after the electric-car maker’s chief executive Elon Musk said he would form a new political party, escalating a feud with US President Donald Trump.