Tesla investors hoping that CEO Elon Musk would stay out of politics after leaving his position in the Trump administration are going to be sorely disappointed—again. Disappointment is rarely good for stock prices.

Tesla shares sank Monday after CEO Elon Musk announced he would form a new political party in an escalation of his feud with President Donald Trump.

Musk has not released an official party platform and has reported a false filing of the proposed political party to the Federal Election Commission. Here's what you need to know about the America Party and what this means for Musk's electric car company: Tesla.