International Consolidated Airlines

Creation of IAG as BA/Iberia holding company

British Airways and Iberia signed a preliminary merger agreement in November 2009. In April 2010, British Airways and Iberia 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

On 4 November 2011, IAG agreed in principle to acquire British Midland International 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

On 8 November 2012, IAG made a cash tender offer to buy Vueling, a Spanish low-cost airline based in Barcelona. The offer was €7 per ordinary share of Vueling, with the total cost of acquisition anticipated to be €113m. It was funded from internal IAG resources. The reported total assets of Vueling as of 30 September 2012 were €805m and in the nine months to 30 September 2012 it had generated profits before tax of €59m. An increased offer of €9.25 was accepted by the Vueling board on 9 April 2013, and received majority shareholder approval on 23 April 2013. IAG took control of Vueling on 26 April 2013.In December 2012, IAG completed the merger of the cargo operations of British Airways, BMI and Iberia into a single business unit, IAG Cargo.

Purchase of Aer Lingus

In January 2015, IAG made a bid of €1.36 billion for Aer Lingus. This was expected to be accepted, after the rejection of two prior bids. In May 2015, the Irish government agreed to sell its stake in Aer Lingus to IAG, as did the Aer Lingus board in late January 2015. The takeover became irreversible on 18 August 2015.

Creation of LEVEL brand

In March 2017, it was announced that a new low cost longhaul airline named LEVEL was to start operating from Barcelona in June 2017.On 29 December 2017, it was announced that IAG bought major parts of defunct Austrian leisure airline Niki including 15 Airbus A321 aircraft and traffic rights in Düsseldorf, Munich, Vienna, Zürich and Palma de Mallorca. It is planned to establish a new Austrian subsidiary of Vueling as a replacement for Niki.

Aborted Norwegian takeover, and group fleet orders

In April 2018, it was reported that IAG was considering a takeover of Norwegian, a low-budget competitor to the group, however by early 2019 IAG had fully disposed of its stake in Norwegian.In June 2019, IAG signed a letter of intent to purchase 200 Boeing 737 MAX aircraft even though at the time of the signing the 737 MAX was still grounded worldwide following the two fatal crashes likely caused by the design of the MCAS system. Aviation analysts have questioned IAG's leadership in making such an order when the 737 MAX design is still being rectified. IAG CEO Willie Walsh, shrugged off the plane's uncertain future. "We're partnering with the Boeing brand", he said. "That's the brand that I'm doing business with. That's the brand that I’ve worked with for years. And it's a brand that I trust".At the 2019 Paris Air Show IAG also agreed to purchase 14 Airbus A321XLR aircraft, 8 for delivery to Iberia and 6 to Aer Lingus, with options for a further 14 of the aircraft.

Investment in Air Europa

In November 2019, IAG announced that it planned to acquire Air Europa from Globalia, for €1 billion. The deal, funded by external debt, and was expected to be completed in the second half of 2020, subject to regulatory approval. On 20 January 2021, IAG announced that it had renegotiated its deal to acquire Air Europa for €500 million as a result of the COVID-19 pandemic. It also negotiated to delay payment to Globalia for 6 years. Completion of the deal is expected to take place in the second half of 2021 and the acquisition is subject to approval by the European Commission.In September 2021, IAG announced that British Airways would terminate its major short- and medium-haul base operations at Gatwick Airport with immediate effect resulting in the cancellation of more than 30 routes. This came after labour negotiations regarding the handover of these operations, most of which were still suspended due to the COVID-19 pandemic, to a newly formed budget subsidiary within IAG failed. In August 2022, IAG converted a loan to Air Europa into a 20% shareholding.