Klarna Bank AB, the Swedish fintech that was once Europe’s most valuable startup, is moving forward with plans for a potential US listing that could be one of the largest listings this year, according to people familiar with the matter.The Stockholm-based buy-now-pay-later giant has recently started having detailed discussions with investment banks to work on an initial public offering that could happen as early as the third quarter, the people said. Klarna is considering seeking a valuation of ...