Shares in Tesla tanked by as much as 7.6% in premarket trading Monday after its CEO Elon Musk said he is forming a new American political party, provoking an irate response from US President Donald Trump.

The electric-vehicle maker’s shares fell 5.3% to $300.71 on Monday, after sliding 1.8% Monday, while the S&P 500 dropped 0.1% and Dow Jones Industrial Average rose 0.9%. It was the sixth consecutive drop for shares after an 8.2% jump on June 23, the day after the company launched a self-driving taxi service in Austin, Texas.

"I am saddened to watch Elon Musk go completely "off the rails," essentially becoming a TRAIN WRECK over the past five weeks,' Trump wrote on social media.

Stocks retreated at the start of a potentially volatile week, as U.S. trading partners rushed to finish trade deals ahead of a July 9th tariff deadline. President Trump said those aligning with the BRICS group of nations will face an additional 10% levy,