This work proposes an optimization model for the power dispatch under a pool-bilateral market. In it, all transactions and also the power traded in the spot market are separated into different networks according to the corresponding current injections. Using the superposition principle (SP), a set of network equations is assigned to every transaction and to the power injections related to the pool (spot market). The model comprises all of the network equations and inequalities representing operational limits. A primal-dual interior point method is used for the resolution of the optimization problem. The line currents, complex voltages, and power generations associated with every transaction and spot market are obtained. Results are presented for a 5-bus and the IEEE 118-bus systems.