Year: 1911
Company: Standard Oil
Result: Broken up into separate oil refining and pipeline companies

Year: 1920
Company: U.S. Steel
Result: No illegal monopoly found

Year: 1982
Company: IBM
Result: Accused of being illegal monopoly; case dropped

Year: 1983
Company: AT&T
Result: Accused of being illegal monopoly; broken up into one long-distance company and seven "baby bell" local phone companies

Year: 1994
Company: Microsoft
Result: Accused of anti-competitive practices; settlement reached

Year: 1998
Company: Microsoft
Result: Accused of using monopoly power to sell other products of 1998, Microsoft's monopoly status was yet to be defined by courts)