Wikipedia
Sigma-Aldrich Corporation was an American multinational chemical, life science and biotechnology company. In September 2014, the German company Merck KGaA announced that it would be acquiring Sigma-Aldrich for $17.0 billion, pending approval from national regulatory agencies. The acquisition was completed in 2015, and Sigma-Aldrich was merged with the Merck Millipore subsidiary of Merck, and the combined business will be known simply as Merck.
Created by the 1975 merger of Sigma Chemical Company and Aldrich Chemical Company, Sigma-Aldrich since grew through various acquisitions until it had over 9,600 employees and was listed on the Fortune 1000 at the time of its acquisition by Merck. Sigma-Aldrich was headquartered in St. Louis and had operations in approximately 40 countries, which are now part of Merck.