Tesla stock has registered its worst week since the onset of the pandemic in March 2020, losing $85bn in market value in a reflection of investors’ doubts about the electric carmaker’s prospects as chief executive Elon Musk runs Twitter at the same time.

Shares in Tesla closed at their lowest point in more than two years on Friday, taking its market capitalisation below $400bn. The stock has lost 18 per cent this week.

Tesla was worth $1.2tn at the beginning of the year. The drop of more than $800bn in value is equal to the combined current market capitalisation of more than 80 of the smallest companies in the S&P 500 index, according to S&P Global Market Intelligence. The carmaker’s market cap this week slipped below that of ExxonMobil, a company reliant on fuelling internal combustion cars.