Tesla's stock price has dropped to its lowest point since March this year, falling 6.3 percent on Friday to close at 263.24 U.S. dollars a share.

The fall in the share price comes after David Morton, Tesla's chief accounting officer, left his post after just one month on the job. And the company's human resources chief Gabrielle Toledano, who is currently on leave, has told Bloomberg that she will not be rejoining the company. 

The Associated Press reports that Tesla is under investigation by the U.S. Securities and Exchange Commission and is facing lawsuits filed by shareholders after CEO Elon Musk tweeted about a plan to take the company private. Just over a fortnight later he said he was not going to pursue that plan. 

Musk told the New York Times in an earlier interview that running the electric automaker has taken a toll on him, as he was working up to 120 hours a week was having trouble sleeping.