Tesla boss Elon Musk has disclosed another $US3.6 billion ($5.2 billion) in stock sales, taking his total near $US40 billion this year and frustrating investors as the company’s shares wallow at two-year lows.

A US securities filing showed he unloaded 22 million shares in the world’s most valuable car maker over three days from Monday to Wednesday.

The sale is the second big chunk of stock he has cashed out since his $US44 billion purchase of Twitter in October.

It isn’t clear if the sales are related to the Twitter acquisition, but they are annoying investors who are upset by a perception he is diverting his focus and resources to Twitter ahead of Tesla.

“It doesn’t put a lot of confidence in the business, or speak volumes for where his attention is at,” said Tony Sycamore, an analyst at brokerage IG Markets, where Tesla is a popular stock among small-time investors.

Tesla investors ‘absolutely furious’

“It’s not a good situation. I’ve spoken to a lot of investors who have Tesla shares and they’re absolutely furious at Elon.”

There was no immediate response to a Reuters request for comment from Tesla and from Musk.

Musk’s 13.4 per cent stake in Tesla is down from about 17 per cent a year ago, according to Refinitiv data.

Tesla’s stock price has halved this year, underperforming both automakers and the broader tech-heavy Nasdaq, which is down about 30 per cent.

The value of Musk’s total selling in the past year comes to nearly $US40b.

Musk’s fortune, mostly tied up in Tesla shares, has fallen with prices this year and he briefly lost his title as the world’s richest person last week, according to Forbes, when he was overtaken by Louis Vuitton boss Bernard Arnault.

Besides Tesla and Twitter, where Musk’s management and tweets are attracting political attention and blowback, Musk also heads rocket company SpaceX and Neuralink, a start-up developing interfaces to connect the human brain to computers.

Tesla, meanwhile, is grappling with lingering logistics challenges and said in October it expected to miss this year’s vehicle delivery target.

The latest share sale comes a month after Musk sold shares worth $US4b in the days after he closed the Twitter deal.

-Reuters