According to three insiders, the US Department of Justice's antitrust investigation into Apple is currently in its later stages and may file a widespread antitrust lawsuit in the first half of this year, targeting the company's strategy to protect its dominant position on the iPhone. Specifically, investigators have investigated how the Apple Watch works better with iPhones compared to other similar brands, and how Apple excludes competitors from its iMessage service. They also reviewed the payment system of the iPhone. Apple's stock price fell nearly 1% during intraday trading on Friday.