The 439 Express Pie-IX is a bus route in Montreal, Quebec, Canada. It is operated by the Société de transport de Montréal (STM). The route operates Monday to Friday during the morning and afternoon rush hour periods. It is a wheelchair accessible route. It serves the boroughs of Rosemont–La Petite-Patrie, Villeray–Saint-Michel–Parc-Extension and Montréal-Nord. It has 16 stops in the northbound direction and 24 stops in the southbound direction.