Postbank, the retail banking unit of Europe's biggest postal service, Deutsche Post AG, began signing up investors for its initial public offering Monday. It's Germany's first major stock market debut in three years. Deutsche Post is listing nearly 82 million shares in Postbank, whose 11.5 million depositors make it Germany's biggest retail bank by number of customers. Postbank on Sunday set a subscription price range of €31.50 to €36.50 (US$38.70 to US$44.85) per share, valuing the bank at between €5.17 billion and €5.99 billion. Investors can subscribe to Postbank shares starting today through June 18. The shares are scheduled to begin trading in Germany on June 21. Deutsche Post chief executive Klaus Zumwinkel said he was confident that the company will be able to place the entire 49.9 percent stake in Postbank with investors. "Postbank is a solid and growth-oriented investment," he said in a statement.