Tesla boss Elon Musk has sold another 19.5 million shares of the electric car maker worth $3.95bn (£3.4bn), filings with the US financial watchdog show.

The news comes less than two weeks after the world's richest man completed his $44bn takeover of Twitter. Tesla's share price has fallen by more than 50% since the start of this year.

Separately, Tesla is recalling just over 40,000 of its vehicles in the US because of a potential problem with their power-steering.

The reason for the latest sales, which took place in the last week, has not yet been disclosed. He sold $8.5bn of Tesla stock in April this year and around another $7bn worth in August.

The latest sale brings the total value of Tesla shares sold by Mr Musk to almost $20bn since he announced earlier this year that he had bought a stake in Twitter.

Also in August, Tesla shareholders approved a three-for-one stock split, which is behind part of the fall in the value of the shares.

Since taking control of Twitter last month Mr Musk has cut around 50% of the company's workforce. He has also blamed "activist groups pressuring advertisers" for a "massive drop in revenue".

Mr Musk tweeted that he had "no choice" but to slash the company's workforce as the firm is losing more than $4m a day.

The shake-up of the social media platform includes charging users $8 for blue check verification marks.