List of largest mergers and acquisitions
The following tables list the largest mergers and acquisitions by decade of transaction. Transaction values are given in the US dollar value for the year of the merger, adjusted for inflation. As of June 2021[update], the largest ever acquisition was the 1999 takeover of Mannesmann by Vodafone Airtouch plc at $183 billion ($284 billion adjusted for inflation). AT&T appears in these lists the most times with five entries, for a combined transaction value of $311.4 billion. Mergers and acquisitions are notated with the year the transaction was initiated, not necessarily completed. Mergers are shown as the market value of the combined entities.
This lists catalogues M&A deals ($20 billion or larger in transaction value) which were confirmed, but for a number of reasons, failed to complete.
