The primary purpose of performing a parallel run of a new system is to verify the new system provides required business functionality. A parallel run is a type of testing that involves running the new system alongside the existing system, allowing the user to compare the outputs of the two systems and verify that they are providing the same results. This helps ensure that the new system is meeting the required business needs and that it is properly configured. According to the ISACA CISA Study Manual, "parallel runs are used to confirm that the new system provides the required business functionality".