Tesla shares sank as much as nine percent on Friday (closing down 6.3 percent) with the departure of key "c-suite" executives and another display of questionable behavior by company chief Elon Musk.

Shares had already lost seven percent for the week before Mr. Musk smoked marijuana and drank whiskey on the podcast hosted by Libertarian comedian and mixed martial arts commentator Joe Rogan.  Within an hour of opening on Friday, the price was down another seven percent.  Hey, if you bought your Tesla stock before 2017, you're still making money.  If you bought more recently than that, or if you really, really want to keep those gains, you might be concerned.

Certainly there is an argument to be made for having a drink after work, or for the legalization of marijuana for recreational use - and it is, in California where the interview took place.  But Tesla drug tests its applicants and existing employees at its plant in the San Francisco Bay Area.  And there are still hundreds of thousands of African-American men rotting in US prisons for petty marijuana convictions. 

This follows a number of incidents that have many wondering what's up with Musk.  Earlier this week, he reignited his feud with the British diver who helped rescue a group of Thai kids from a flooded cave.  Before that was the uncertainty created by an aborted idea to take the company public and verbal sparring with fund managers who control large amounts of Tesla stock.  The company had been under scrutiny as production of the much ballyhooed Model 3 got bogged down.

The volatility may have been too much for one "c-suite" executive.  A month ago, Tesla welcomed its new chief accounting officer Dave Morton, who was hired away from Seagate.  But in a filing with the Securities and Exchange Commission on Friday, Tesla said Mr. Morton made a quick dash for the exit.

"Since I joined Tesla on Aug. 6, the level of public attention placed on the company, as well as the pace within the company, have exceeded my expectations," said Morton, in a statement that was included in the filing.  "As a result, this caused me to reconsider my future.  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."

Friday was the last day for Sarah O'Brien, Tesla's vice president of communications.  Human Resources chief Gabrielle Toledano also left the company, as well as treasurer and vice president for finance Susan Repo who departed in March.