The Monsanto Company () was an American agrochemical and agricultural biotechnology corporation that existed from 1901 until 2018 when it was acquired by Bayer as part of its crop science division. It was headquartered in Creve Coeur, Missouri. Monsanto developed Roundup, a glyphosate-based herbicide, in the 1970s, and became a major producer of genetically engineered crops.
Monsanto was one of four groups to introduce genes into plants in 1983, and was among the first to conduct field trials of genetically modified crops in 1987. It was one of the top 10 US chemical companies until it divested most of its chemical businesses between 1997 and 2002, through a process of mergers and spin-offs that focused the company on biotechnology. Monsanto was one of the first companies to apply the biotechnology industry business model to agriculture, using techniques developed by biotech drug companies. In this business model, companies recoup R&D expenses by exploiting biological patents.Monsanto's roles in agricultural changes, biotechnology products, and lobbying of government agencies, and roots as a chemical company, resulted in controversies. The company once manufactured controversial products such as the insecticide DDT, PCBs, Agent Orange, and recombinant bovine growth hormone. Its seed patenting model was criticized as biopiracy and a threat to biodiversity.In September 2016, Bayer announced its intent to acquire Monsanto for US$66 billion. After gaining US and EU regulatory approval, the sale was completed on June 7, 2018.