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., the largest ever acquisition was the 1999 takeover of Mannesmann by Vodafone Airtouch plc at $183 billion. 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.
Free market enterprises
1870s
Top 2 M&A deals worldwide by value from 1870 to 1879:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1874 | Honeybrook Coal Company | Wilkesbarre Coal and Iron Company | 0.01 | |
| 2 | 1879 | Pacific Coast Oil Company | Star Oil | 0.001 |
1880s
Top 2 M&A deals worldwide by value from 1880 to 1889:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1884 | New York Gas Light Company | Manhattan Gas Light Company Metropolitan Gas Light Company Municipal Gas Light Company Knickerbocker Gas Light Company Harlem Gas Light Company | 0.045 | |
| 2 | 1883 | Buffalo, Pittsburgh and Western Railroad | Buffalo, New York and Philadelphia Railway Olean and Salamanca Railroad Oil City and Chicago Railroad Company | 0.02085 |
1890s
Top 2 M&A deals worldwide by value from 1890 to 1899:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1899 | American Spirits Manufacturing Company | Kentucky Distilleries and Warehouse Company Spirits Distributing Company | 0.125 | |
| 2 | 1899 | Pullman Palace Car Company | Wagner Palace Car Company | 0.074 |
1900s
Top 3 M&A deals worldwide by value from 1900 to 1909:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1901 | Carnegie Steel Company | Federal Steel Company National Steel Company | 0.492 | |
| 2 | 1907 | New York, New Haven and Hartford Railroad Company | Boston and Maine Corporation | 0.310 | |
| 3 | 1909 | Interborough Rapid Transit Company | Metropolitan Street Railway | 0.222 |
1910s
Top 3 M&A deals worldwide by value from 1910 to 1919:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1915 | Midvale Steel Company | Remington Arms Company Worth Brothers Company | 0.100 | |
| 2 | 1915 | United Dry Goods | Associated Merchants Company | 0.050 | |
| 3 | 1918 | General Motors | United Motors Company | 0.045 |
1920s
Top 5 M&A deals worldwide by value from 1920 to 1929:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1928 | Consolidated Gas Company of New York | Brooklyn Edison Company | 1.0 | |
| 2 | 1929 | Niagara and Eastern Power Corporation | MohawkHudson Power Corporation Northeastern Power Corporation | 0.665 | |
| 3 | 1928 | United Light and Power Company | American Light and Traction | 0.522 | |
| 4 | 1928 | Hodenpyl & Hardy | Stevens & Wood | 0.500 | |
| 5 | 1928 | Middle West Utilities | National Electric Power National Public Service New England Public Service Inland Power and Light | 0.400 |
1930s
Top 5 M&A deals worldwide by value from 1930 to 1939:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1930 | Pacific Gas and Electric Company | Great Western Power Company San Joaquin Light and Power Corporation Midland Counties Public Service Corporation | 0.650 | |
| 2 | 1932 | Sinclair Consolidated Oil Corporation | Prairie Oil and Gas Prairie Pipe Line Company | 0.542 | |
| 3 | 1934 | Republic Steel | Corrigan-McKinney Steel Corporation | 0.323 | |
| 4 | 1931 | Bethlehem Steel | Pittsburgh Steel Company | 0.080 | |
| 5 | 1932 | Studebaker Corporation | White Motor Company | 0.026 |
1940s
Top 5 M&A deals worldwide by value from 1940 to 1949:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1945 | Consolidated Edison | Brooklyn Edison Company New York and Queens Light and Power Company | 1.2 | |
| 2 | 1948 | Central New York Power Corporation | New York Power and Light Corporation Buffalo Niagara Electric Corporation | 0.500 | |
| 3 | 1945 | Pittsburgh Coal Company | Consolidation Coal Company | 0.160 | |
| 4 | 1948 | Long Island Lighting Company | Queens Borough Gas and Electric Company Nassau & Suffolk Lighting Company | 0.140 | |
| 5 | 1941 | Celanese Corporation | Celluoid Corporation | 0.096 |
1950s
Top 10 M&A deals worldwide by value from 1950 to 1959:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1959 | General Telephone | Sylvania Electric Products | 1.8 | |
| 2 | 1957 | Armco | National Supply Company | 0.768 | |
| 3 | 1957 | American Can Company | Marathon Corporation | 0.717 | |
| 4 | 1955 | Monsanto | Lion Oil | 0.550 | |
| 5 | 1956 | Continental Can Company | Robert Gair Company | 0.549 | |
| 6 | 1954 | Olin Industries | Mathieson Chemical | 0.500 | |
| 7 | 1955 | Sunray Oil Corporation | Mid-Continent Petroleum Corporation | 0.486 | |
| 8 | 1955 | Sperry Corporation | Remington Rand | 0.466 | |
| 9 | 1953 | Gulf Oil | Warren Petroleum Corporation | 0.420 | |
| 10 | 1954 | Hudson Motor Car Company | Nash-Kelvinator | 0.355 |
1960s
Top 10 M&A deals worldwide by value from 1960 to 1969:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1969 | Atlantic Richfield | Sinclair Oil Corporation | 3.7 | |
| 2 | 1965 | Union Oil | Pure Oil | 1.5 | |
| 3 | 1968 | Hunt-Wesson | Canada Dry McCall Corporation | 1.0 | |
| 4 | 1969 | Xerox Corporation | Scientific Data Systems | 0.925 | |
| 5 | 1967 | Rockwell-Standard | North American Aviation | 0.922 | |
| 6 | 1968 | Sun Oil | Sunray DX Oil Company | 0.763 | |
| 7 | 1965 | Continental Oil Company | Consolidation Coal | 0.620 | |
| 8 | 1961 | American-Marietta Corporation | Glenn L. Martin Company | 0.600 | |
| 9 | 1968 | Control Data Corporation | Commercial Credit Company | 0.582 | |
| 10 | 1967 | Studebaker Corporation | Worthington Corporation | 0.550 |
1970s
Top 15 M&A deals worldwide by value from 1970 to 1979:| Rank | Year | Purchaser | Purchased | Transaction value | Inflation adjusted |
| 1 | 1979 | Shell Oil Company | Belridge Oil Company | 3.65 | |
| 2 | 1976 | General Electric | Utah International | 2.17 | |
| 3 | 1979 | RCA | CIT Financial | 1.3 | |
| 4 | 1979 | Exxon | Reliance Electric | 1.2 | |
| 5 | 1978 | United Technologies | Carrier Corporation | 1.0 | |
| 6 | 1979 | Mobil | General Crude Oil | 0.765 | |
| 7 | 1976 | Atlantic Richfield | Anaconda Copper | 0.760 | |
| 8 | 1978 | R. J. Reynolds Industries | Del Monte Corporation | 0.620 | |
| 9 | 1978 | Johns Manville | Olinkraft Inc | 0.585 | |
| 10 | 1977 | Kennecott Copper | Carborundum Corporation | 0.567 | |
| 11 | 1978 | Philip Morris | Seven-Up Bottling Co | 0.520 | |
| 12 | 1978 | Beatrice Foods | Tropicana Products | 0.488 | |
| 13 | 1977 | Unilever | National Starch and Chemical | 0.485 | |
| 14 | 1974 | Burmah Oil | Signal Oil & Gas | 0.480 | |
| 15 | 1979 | American Brands | Franklin Life Insurance | 0.465 |