By Lars Mucklejohn Buy-now pay-later (BNPL) giant Klarna has filed for an initial public offering (IPO) in the US, formally starting proceedings for a blockbuster stock market debut. The Swedish fintech company confidentially submitted the relevant paperwork to the Securities and Exchange Commission (SEC), it said last night. Klarna added that the number of shares to be offered and the price range for the planned IPO have not yet been determined, giving no hints on the valuation it is seeking. It was reported earlier this year that the firm was in talks with banks about a New York IPO and was …