Chief accounting officer Dave Morton gave notice on Tuesday that he was resigning less than a month into the job, according to a filing. Tesla announced several promotions, including a replacement for O'Brien, in a blog post on Friday, but did not name a new chief accounting officer.
Elon Musk has smoked marijuana in an interview with podcaster Joe Rogan, which was broadcast live.
Some people speculated that he was high when he tweeted last month that he was considering taking Tesla private, citing his proposal of $US420 a share - "420" is a reference to weed. Tesla shares, down just 1 percent after Musk's appearance on the Rogan podcast overnight, fell as much as 10 percent after Morton's resignation and were still down 5.1 percent at $266.75 in late morning trading. As for the figure, Musk said that $420 "seemed like better karma" than $419. Musk eventually abandoned his plan to go private on August 25 after CNBC reported Morgan Stanley was planning to be retained to seek financing for a transaction, suggesting funding for a deal hadn't been secured. Of his past experiences with smoking, the actor had this to say:"I'm not a regular smoker of weed", he mused. "I don't find that it is very good for productivity".
Amazon hits $1 trillion market value milestone
Shares in the e-commerce giant rose almost 2 percent to a high of $US2,050.50 in morning trade before slipping back. Amazon has become the second USA public company to cross the $1 trillion valuation threshold this year.
That about-face has sparked an investigation by securities regulators reportedly focusing on the veracity of Musk's claim that he had secured funding for the deal.
"I want to be clear that I believe strongly in Tesla, its mission, and its future prospects, and I have no disagreements with Tesla's leadership or its financial reporting", he said.
Tesla has told investors it expects to turn a profit in the second half of this year, a forecast the company's head of investor relations, Martin Viecha, reiterated at a conference earlier this week sponsored by RBC Capital Markets, RBC analyst Joseph Spak wrote in a note on Thursday.
Tesla shares were down almost 9 percent premarket. The report, which was published by electric car-themed news site InsideEVs, estimated that the Tesla Model 3, Model S, and Model X, were the Top 3 electric cars in the U.S. in August.