The European Union is poised to warn Apple to open up its highly secretive iPhone operating system to rivals, or face a hefty fine. Sources say that EU regulators will announce, under the EU's new Digital Markets Act, that Cupertino, California-based Apple must comply with strict new regulations and make its operating system compatible with other technologies. This announcement marks a step away from a formal investigation, but the EU aims to force Apple to redesign its services to allow rivals access to the iPhone's operating system. If Apple fails to comply, the EU may later decide to launch a formal investigation, which could ultimately lead to fines of up to 10% of Apple's global annual turnover. (Jin Shi)