For the treatment of major depressive disorder (MDD), which affects more than 17 million people in the United States, there are multiple prescription therapies that are used to treat depressive symptoms. Consistent with published guidelines, physicians most commonly prescribe a selective serotonin reuptake inhibitor (SSRI) or a serotonin/norepinephrine reuptake inhibitor (SNRI) as first-line treatment. Nevertheless, treatment selection is highly individualized. Therapies such as bupropion (various brands and generics), mixed serotonin modulators, and atypical antipsychotics are also widely used—particularly once an MDD patient fails two or three lines of therapy of adequate dose and duration—both as monotherapy and as part of a combination regimen. Using patient-level claims data, this report explores the position of the leading maintenance therapies in the treatment of MDD and assesses the impact of recent events in the MDD market on treatment patterns, most notably the entrance of generic versions of Eli Lilly’s SNRI Cymbalta (duloxetine)—an event that is increasing the already extensive generics presence in the MDD market—and the launch of two new antidepressants in the United States (Allergan/Pierre Fabre’s Fetzima [levomilnacipran] and Lundbeck/Takeda’s Brintellix [vortioxetine]). The report provides a quantitative analysis of treatment patterns and share by line of therapy among newly diagnosed MDD patients, as well as progression between lines, duration of treatment on each line, and use of concomitant treatment. Among recently treated MDD patients, the report quantifies a drug’s source of business compared with its competitors and details which drugs precede others through an analysis of add-versus-switch patterns. Additional analyses explore persistency and compliance by product.