Apple will be hit with an EU antitrust charge over its NFC chip technology, people familiar with the matter said, a move that puts it at risk of a possible hefty fine and could force it to open its mobile payment system to rivals.

The iPhone maker has been in European Union antitrust chief Margrethe Vestager’s crosshairs since June last year when she launched an investigation into Apple Pay.

Preliminary concerns were Apple’s NFC chip that enables tap-and-go payments on iPhones, its terms and conditions on how mobile payment service Apple Pay should be used in merchants’ apps and websites, and the company’s refusal to allow rivals access to the payment system.

The European Commission has since narrowed its focus to just the NFC chip, which can only be accessed by Apple Pay, one of the sources said.

The EU competition enforcer is now preparing a charge sheet known as a statement of objections, which could be sent to Apple next year, one of the sources said. Such documents typically set out practices considered anticompetitive by the regulator.

The commission, which has three other cases against Apple, declined to comment. It can fine companies up to 10% of their global turnover for violating EU rules, which based on Apple’s 2020 revenue could come to US$27.4-billion.

Apple, which has cited privacy and safety issues for its policy on Apple Pay, was not immediately available for comment.

Apple’s shares were down 1% at $139.6 in early trade.