FRANKFURT, Germany—German prosecutors have charged the former CEO of payments company Wirecard and two other ex-managers with fraud and false accounting in connection with the firm’s collapse last year amid allegations that much of its revenue and assets were faked. Prosecutors in Munich said Monday that ex-CEO Markus Braun signed off on financial reports he knew were false. They said the firm booked nonexistent revenue it attributed to multiple partnerships in other countries and used fake documents to show it had funds that it did not. The firm’s former head of accounting and the managing director of a Dubai-based subsidiary also were charged. The fraud cost banks 3.1 billion euros ($3.4 billion) in loans and writedowns, according to the prosecutors’ statement. One of the central figures in the case, the company’s former chief operating officer Jan Marsalek, is being sought by authorities, prosecutors said. Braun’s attorney said the charges were …