The official announcement from Avast CEO Vincent Steckler can be found at https://blog.avast.com/avast-and-avg-a-future-together.
According to the Fortune magazine story at http://fortune.com/2016/07/07/avg-avast-deal-ceo-gary-kovacs/, "The combined company would create the world’s biggest antivirus software firm by number of active users, exceeding even Microsoft’s market share of antivirus technology on consumer devices".