Tesla shares sank after CEO Elon Musk bit the capitalist hand that feeds the company, chafing at "boring" questions and lashing out at day traders.

Shares had been trading at US$305.55 on Wednesday afternoon, before a public earnings call with investors and financial analysts.  Things started to go awry when analyst Toni Sacconaghi of Sanford C. Bernstein asked about Tesla's ability to reach a gross margin target of 25 percent on the Model 3, then about its projected capital requirements.

"Excuse me," Musk interrupted.  "Next.  Boring bonehead questions are not cool.  Next?"

But Musk didn't care much for the next question from Joseph Spak from RBC Capital Markets, who asked how many people who reserved the Model 3 are actually buying the electric car.

Musk stayed silent for 10 seconds, perhaps rolling his eyes, and replied:  "Sorry.  These questions are so dry.  They're killing me."

At one point, Musk even told one analyst: "We have no interest in satisfying the desires of day traders.  I couldn't care less.  Please sell our stock and don't buy it."

And some may have taken him up on that offer, because Tesla stock fell 5.55 percent on Thursday, winding up at $284.45.  Tesla stock has had its volatile periods, but until now Wall Street didn't question its wunderkind chief.  The terse exchange during what is usually a chummy affair might interrupt Tesla's drive to free itself of venture capital and become a stand alone company.

"The analysts on the call represent the providers of capital that Tesla has throughout its history depended upon," wrote Adam Jonas, who covers Tesla for Morgan Stanley.

"Let's just say that Elon's behavior on the call should give even the uberbulls pause," wrote Brian Johnson of Barclays Capital, who described the conference call as "downright bizarre".