One of Italy's leading multi-service companies, A2A was listed on the Milan Stock, following the merger of AEM Milano (Municipal Electricity Company) and ASM Brescia (Municipal Services Company). AEM and ASM were founded by their respective municipalities in the early 20th century to produce and distribute electricity and provide other public utility services.

The company operates in electricity, gas, waste management, and the integrated water cycle, with its customer base primarily concentrated in Lombardy. In 2010, the group employed over 12,000 people and generated revenues of approximately 6 billion euros.