Alstom SA (French: [alstɔm]) is a French multinational rail transport systems manufacturer. It is active in the fields of passenger transportation, rail services, signalling, and locomotives, producing high-speed, suburban, regional and urban trains along with trams.
The company and its name (originally spelled Alsthom) were formed by a merger between the electric engineering division of Société Alsacienne de Constructions Mécaniques (Als) and Compagnie Française Thomson-Houston (thom) in 1928. Significant acquisitions later included the Constructions Électriques de France (1932), shipbuilder Chantiers de l'Atlantique (1976), and parts of ACEC (late 1980s).