Klarna-Affirm Rivalry Reshaping One of the Biggest Fintech IPOs

Even by Sebastian Siemiatkowski’s standards, it’s been a wild month.

The chief executive officer of buy now, pay later giant Klarna Group Plc started March on a high when he formally filed to list his 20-year-old company.

Days later, he edged out longtime rival Affirm Holdings Inc. when he landed a deal with a fintech backed by the biggest retailer on the planet, Walmart Inc. What should have been good news, though, soon turned to bad: The announcement put pressure on Affirm’s shares, which are considered a key benchmark for Klarna’s own offering. Within a week, Klarna was also ...