Tesla chief Elon Musk sold nearly $4 billion worth of shares in the electric car company, SEC filings showed Tuesday, more than a week after he closed his $44 billion acquisition of Twitter.

Musk has been pushing for ways to pay for the massive deal, for which he took on billions of dollars in debt and earlier sold $15.5 billion worth of shares in Tesla.

On Tuesday, documents filed with the US Securities and Exchange Commission (SEC) indicated that he had disposed of more than another 19 million shares, worth in excess of $3.9 billion.

Musk took control of Twitter and fired its top executives in late October, after a drawn-out back-and-forth between the world's richest person and the influential social media company.

The billionaire initially tried to step back from the deal after his unsolicited offer was accepted in April.

He said in July that he was canceling the contract because he had been misled by Twitter over the number of fake "bot" accounts, allegations rejected by the company.

After Musk sought to terminate the sale, Twitter filed a lawsuit to hold the entrepreneur to the agreement. With a trial looming, he revived his takeover plan.

- Overhaul -

On Friday, Twitter sacked half of its 7,500-strong staff as its new owner launched an overhaul of the company.

Jack Dorsey, who co-founded Twitter in 2006 and stepped down as CEO last year, tweeted to apologize for growing the site too quickly, following news of the firings.

Musk has been searching for ways for the social media platform to make money after the buyout, including an idea to charge users $8 a month for verified accounts.

The move would help overcome a potential loss of advertisers, Twitter's main source of revenue, after many top brands put their ad buys on hold, uneasy about Musk's well-known disdain for content controls.

Musk's actions and statements since taking over the reins of Twitter have prompted concern, including warnings from the United Nations.

UN rights chief Volker Turk has urged Musk to make respect for human rights a priority for the social network.

Musk has insisted that content moderation remains a priority for Twitter and that he would create a council dedicated to the task.

Musk's decision to pull Twitter off the stock market has allowed him to make major changes quickly, but it also took the company more heavily into debt, a risky choice for a money-losing business.

Tesla recalls more than 40,00 vehicles

Tesla issued a recall in the United States to just over 40,000 vehicles for a possible problem in the electric power steering system, an issue that was being fixed remotely.

The US road safety agency, the NHTSA, reported a possible defect in this system in a filing dated November 1 and published on Tuesday.

"Reduced or lost power steering assist does not affect steering control, but could require greater steering effort from the driver, particularly at low speeds," the agency said.

The affected vehicles - Model S and Model X manufactured between 2017 and 2021 - can be remotely fixed at no charge.

According to Tesla, 97 percent of the concerned vehicles had an update as of November 1.

Tesla already made several recalls in the United States this year to remotely modify potentially problematic features.

At the end of September, the company recalled more than one million vehicles because of a risk of injury in operating the car windows.