The efficacy of TMS in major depressive disorder (MDD) has markedly improved since the pivotal sham-controlled trials. While this enhanced efficacy has been attributed to use of longer treatment courses, the impact of number of treatment sessions on efficacy has not been adequately evaluated. The study device is the Neuronetics, Inc. NeuroStar® TMS Therapy System (K160703, K201158).The study is a retrospective analysis of real-world data from commercial centers. The data will be gathered from the Neuronetics database called TrakStar which collects records of each patient's treatment. The data will be used only as applicable to the objectives of this study.