Sources say Target Corp., the fourth-largest U.S. retailer, is in the early stages of developing its own mobile wallet. That would put it in the ranks of those like Wal-Mart who are offering products competing with Apple Pay. The application, which would let buyers pay for goods using their mobile phones, could launch as early as next year, but it is too early to predict, said two of the sources. The sources say Target favors processing transactions using scanning technology to communicate with payment terminals.