LONDON—Bitcoin rose above $50,000 on Tuesday to a new record high, building on a rally fuelled by signs that the world’s biggest cryptocurrency is gaining acceptance amongst mainstream investors. Bitcoin hit a new high of $50,602 and was last up 5 percent at $50,300. It has risen around 72 percent so far this year, with most of the gains coming after electric carmaker Tesla said it had bought $1.5 billion in bitcoin. It also said it would accept the currency as payment. But Tesla was only the latest in a string of large investments that have vaulted bitcoin from the fringes of finance to company balance sheets and Wall Street dealing desks, as U.S. firms and traditional money managers have started to buy a lot of it. “The recent market conditions and events both in the crypto space and the financial world at large put such a price movement within …