How it started
Creation of IAG as BA/Iberia holding company
British Airways and Iberia signed a preliminary merger agreement in November 2009. In April 2010, they signed a full merger agreement, with an intended completion date of late 2010, subject to securing the necessary regulatory approvals. The merger between British Airways and Iberia was completed on 21 January 2011, and shares in the new holding company IAG began trading in London and Madrid on 24 January.
On 6 October 2011, IAG created Iberia Express, a new low-cost airline to operate short- and medium-haul routes from IAG's Madrid hub and provide transfer feed onto Iberia's longhaul network. Iberia Express began operations on 25 March 2012.
Purchase of BMI (2011)
On 4 November 2011, IAG agreed in principle to acquire British Midland International (BMI) from Lufthansa, in a deal which would increase IAG's share of slots at Heathrow airport from 45% to 54%. On 22 December 2011, IAG agreed a binding deal with Lufthansa to acquire BMI for £172.5 million. On 30 March 2012, the purchase was approved, subject to the condition that the combined group divest itself of 12 daily slots and lease two daily slots at Heathrow airport. The acquisition was completed on 20 April 2012, and the BMI fleet and routes were integrated into the British Airways schedule throughout 2012. Slaughter and May advised IAG on the BMI acquisition.
Purchase of Vueling, and creation of IAG Cargo (2012)
From Wikipedia’s article on International Airlines Group, shared under CC BY-SA 4.0.2