'It's legal, right?' - Elon Musk smokes marijuana on podcast leaving Tesla stocks to plunge

Elon Musk took a drag from a joint. Credit: Joe Rogan Experience

Elon Musk managed to send shares in Tesla tumbling by 7% after he was filmed smoking marijuana during the recording of a podcast.

The 47-year-old technology billionaire had appeared in a two-and-a-half hour recording with comedian Joe Rogan, later shown on YouTube, where the pair lit up a combined marijuana-tobacco joint.

Musk and Rogan had been filming in California where marijuana is legal, although Musk had to ask for reassurance before indulging.

The markets did not take well to the appearance, with shares in Tesla Inc falling on Friday morning.

On the same day, Tesla announced that chief accounting officer Dave Morton had resigned after a month, citing public attention and the fast pace of the post.

During the show, Musk said he "almost never" smoked.

"I'm not a regular smoker of weed," Musk said.

"I don't actually notice any effect...I don't find that it is very good for productivity."

It comes just weeks after Musk became embroiled in a public row with British cave diver Vernon Unsworth, who he accused of being a "paedophile".

Musk was forced into an apology after Mr Unsworth threatened to sue.