Wall Street firms are in a race to transform stocks and other traditional assets into digital tokens using the technology that underpins bitcoin and other cryptocurrencies. While tokenized stocks haven’t yet crossed into the U.S., the world’s biggest market, traders are buying and selling them in markets throughout Europe and Asia. Crypto proponents say tokenized stocks can be a game-changer, offering 24/7 trading and the chance to own fractions of shares that might come with eye-watering prices.