Tesla shares fell nearly 8% on Monday after CEO Elon Musk's plans to launch a new U.S. political party reignited concerns about his commitment to the company's future as it struggles with declining sales.

Tesla stock lost nearly 7% Monday after Elon Musk announced plans of launching the “America Party.” William Blair downgraded TSLA shares.

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.