Elon Musk's electric vehicle company Tesla has revealed it has sold 75 percent of its bitcoin holdings amid a downturn in the cryptocurrency market. In the company's Q2 2022 financial report it was revealed that US$936 million in cash had been added to its balance sheet following the sale of the majority of its cryptocurrency. It follows the company's US$1.5 billion investment in bitcoin last year, during which it briefly accepted the cryptocurrency for payment for cars, but then changed its mind. Musk, the controversial billionaire who is being sued by Twitter to force him to complete his US$44 billion…