Buy now, pay later firm Klarna, which filed for an initial public offering last week, has grabbed retailer Walmart away from rival Affirm Holdings as a customer. Affirm stock dropped on the news.Sweden-based Klarna has forged an exclusive deal with Walmart,

Swedish fintech firm Klarna will be the exclusive provider of buy now, pay later loans for Walmart, taking a coveted partnership away from rival Affirm, CNBC has learned.

Klarna Group Plc has filed for a U.S. initial public offering at a weak moment for company debuts, though the fintech player thinks it can offer investors more than just its buy-now-pay-later products.