Almost one year after the fintech giant Stripe struck a $1.1 billion deal to acquire the stablecoin startup Bridge, two other big corporate players want to scoop up a stablecoin firm of their own. The U.S. crypto exchange Coinbase and the payments giant Mastercard have each held advanced acquisition talks to buy London-based BVNK, according to six sources familiar with the dealings, who asked for anonymity to talk about confidential business discussions. The terms and winning bidder haven’t been...