Elon Musk has returned to federal court in San Francisco to give evidence in a class action lawsuit filed by Tesla investors alleging he misled them with a tweet.

The tweet, which resulted in a 40 million dollar (£32 million) settlement with securities regulators, claimed he had lined up the financing to take Tesla private in a deal that never came close to happening.

The trial hinges on the question of whether a pair of tweets that Mr Musk posted on August 7 2018 damaged Tesla shareholders during a 10-day period leading up to a Musk admission that the buyout he had envisioned was not going to happen.

Mr Musk, who said he “had trouble sleeping last night and unfortunately I am not at my best”, said that it was important for jurors to know that he “felt that funding was secured” due to his ownership of “SpaceX stock alone”.

“Just as I sold stock in Tesla to buy Twitter. … I didn’t want to sell Tesla stock but I did sell Tesla stock,” he said of the stock sale to make up for the lack of funding from other sources for his 44 billion dollar (£35.5 billion) deal to take Twitter private.

“My SpaceX shares alone would have meant that funding was secured,” Mr Musk said.