Mastercard Outbids Visa for Tiny Firm in $30 Trillion Sector (1)

Few investors will have heard of Earthport Plc. But the company has just become the target in a bidding war between Mastercard Inc. and Visa Inc.

Earthport’s shares, listed on London’s small-cap Alternative Investment Market, quadrupled over the last four weeks, and rose 27 percent by mid-morning after Mastercard’s bid on Jan. 25. The shares jumped again in late-afternoon trading, to 36.5 pence, when Visa said it was considering its options.

The 21-year-old firm isn’t a startup, and despite its name it isn’t playing in the private space travel game. Earthport is a cross-border payments network. It uses a cloud-based ...