Tesla Inc. plunged Friday, capping its worst week since 2016, after Elon Musk told the New York Times that no one saw or reviewed his tweet about the plan to take the company private before he posted it. Musk, Tesla\u2019s chief executive officer and chairman, told the Times that he typed the take-private tweet as he drove himself to the airport on Aug. 7. The tweet said: \u201cAm considering taking Tesla private at $420. Funding secured.\u201d The billionaire frequently teared up in an interview and discussed the personal strain of leading the electric-car maker, the newspaper said. The stock was nowhere near that price on Friday as it tumbled 8.9 percent, the most in two years, to close at $305.50. The fourth straight day of declines has wiped out Tesla\u2019s year-to-date gains and pushed the shares down 14 percent this week - their most dire one since February 2016. In an hourlong interview with the newspaper, Musk also detailed his frequent use of the sleep-aid Ambien - a drug he\u2019s discussed using before, and whose well-known side effects include sleepwalking. \u201cIt is often a choice of no sleep or Ambien,\u201d he told the newspaper. Rather than put him to sleep, the drug has sometimes led Musk to spend his nights on Twitter, worrying some board members, the newspaper said, citing a person familiar with the board\u2019s thinking. Mounting Scrutiny The going-private tweet has set off a firestorm, causing the stock to jump but also prompting mounting scrutiny, including a Securities and Exchange Commission investigation. Almost a week later, the CEO said the basis for that statement were conversations with Saudi Arabia\u2019s Public Investment Fund, which first expressed interest in helping take the company private in early 2017. Tesla\u2019s board has since clarified that it hasn\u2019t received a formal proposal from Musk, nor has it concluded whether going private would be advisable or feasible. This week, Musk was said to have received a subpoena for more information, according to a person familiar with the matter. One funding possibility being considered for the potential privatization is for Musk\u2019s rocket company SpaceX to help bankroll the deal and take a stake in Tesla, the New York Times said, citing people familiar with the matter. Efforts are also under way to recruit an executive to take some pressure off Musk, the newspaper said, citing people briefed on the search. A couple of years ago, Tesla approached Facebook Inc. executive Sheryl Sandberg about the job, Musk told the newspaper, but added that no active search is taking place currently \u201cto the best of my knowledge.\u201d \u201cIf you have anyone who can do a better job, please let me know,\u201d Musk told the Times. \u201cThey can have the job.\u201d Factory Progress Despite the frenzy over Tesla\u2019s future, production of the pivotal Model 3 sedan - which has frequently kept Musk at the Fremont factory overnight - is defying the odds and going well, according to Evercore ISI analysts. Output is well on track for weekly production goals, and set for a significant boost, the analysts wrote Thursday after touring the plant. Bloomberg\u2019s Model 3 Tracker also shows significant improvement this month. In the interview, Musk said he had sacrificed family milestones in the race to meet Tesla production targets, nearly missing his brother\u2019s wedding where he was best man. Friends had approached him with concerns about his well-being, the New York Times said. He called the period \u201cexcruciating,\u201d the newspaper reported. \u201cThis past year has been the most difficult and painful year of my career.\u201d Musk told the newspaper that he didn\u2019t recall communications from the board at all and that he \u201cdefinitely did not get calls from irate directors.\u201d He later amended the comment through a spokeswoman, saying lead independent director Antonio Gracias had contacted him about the Aug. 7 tweet. Musk agreed not to tweet again on the possible privatization without discussing it with the board, the spokeswoman said.