Tesla shares slide as Elon Musk admits to "difficult and painful year"

Last Updated Aug 17, 2018 5:09 PM EDT

Tesla's stock price slid for a fourth straight day as investors digested reports of a federal securities probe and CEO Elon Musk's emotional interview with the New York Times.

The Securities and Exchange Commission is reportedly investigating an August 7 tweet by Musk in which he proposed taking the electric car maker private and said he had secured funding for the transaction. The billionaire told the Times that no one at Tesla reviewed his tweet, which he said he typed while driving himself to the airport.

Asked if he regretted the tweet, he told the Times, "Why would I?"

The Wall Street Journal also reports that the SEC is examining if Tesla misled investors about production problem for its Model 3 sedan. 

On Friday, Tesla shares fell 8.9 percent to close at $305.50. As part of the plan to go private, Musk proposed paying stockholders $420 a share. The decline in Tesla shares since the executive floated the idea suggests investors are skeptical he can pull it off, analysts say. Tesla's stock price is down 1 percent for the year.

Amid mounting questions about such a deal, Musk said that Saudi Arabia's Public Investment Fund had expressed interest in participating. Tesla's board has since created a committee of independent directors to evaluate the plan

"Difficult and painful"

Musk repeatedly teared up during the Times interview, telling the newspaper that he almost missed his brother's wedding as he worked 120-hour weeks and referring to an "excruciating" period of trying to meet the company's vehicle production goals.

He also described his use of the drug Ambien to sleep, a topic he's talked of before. 

"This past year has been the most difficult and painful of my career," Musk told the Times, which cited people briefed on the matter as saying Tesla is working to recruit an executive to take some of the heat off of Musk. "If you have anyone who can do a better job, please let me know," Musk told the Times, adding: "They can have the job."

Musk's seemingly fragile psychological state put pressure on Tesla's board to take action, said Erik Gordon, a University of Michigan business and law professor.

"If the board does not get him out of this slot at a minimum on a leave of absence basis, I think the board is going to be seen by a lot of people who love the company as being derelict in their duties," he said. "You can love the company, you can love Musk and hate having him be the CEO at this point."

Musk's erratic behavior has drawn attention in other ways of late. In May he rebuked stock analysts for asking "boring, bonehead" questions, while in July he accused a British caver involved in the rescue of a Thai youth soccer team from a flooded cave of being a pedophile

Although Musk apologized after both outbursts, they raised questions about his frame of mind.

-- The Associated Press contributed to this report.