Bayer AG (/ˈbaɪ.ər/, commonly pronounced /ˈbeɪər/;[3] German: [ˈbaɪɐ]) is a German multinational pharmaceutical and biotechnology company and one of the largest pharmaceutical companies in the world. Headquartered in Leverkusen, Bayer’s areas of business include pharmaceuticals; consumer healthcare products, agricultural chemicals, seeds and biotechnology products. The company is a component of the Euro Stoxx 50 stock market index.[4]

Bayer was founded in 1863 in Barmen as a partnership between dye salesman Friedrich Bayer and dyer Friedrich Weskott. As was common in this era, the company was established as a dyestuffs producer. The versatility of aniline chemistry led Bayer to expand their business into other area, and in 1899 Bayer launched the compound acetylsalicylic acid under the trademarked name Aspirin. In 1904 Bayer received a trademark for the “Bayer Cross” logo, which was subsequently stamped onto each aspirin tablet, creating an iconic product that is still sold by Bayer. Other commonly known products initially commercialized by Bayer include heroin, phenobarbitol, polyurethanes, and polycarbonates.

In 1925 Bayer merged with five other German companies to form IG Farben, creating the world’s largest chemical and pharmaceutical company. Following World War II, the Allied Control Council seized IG Farben’s assets[a][5] because of its role in the Nazi war effort and involvement in the Holocaust including using slave labour from concentration camps and humans for dangerous medical testing, and production of Zyklon B, a chemical used in gas chambers.[6] In 1951 IG Farben was split into its constituent companies, and Bayer was reincorporated as Farbenfabriken Bayer AG. Bayer played a key role in the Wirtschaftswunder in post-war West Germany, quickly regaining its position as one of the world’s largest chemical and pharmaceutical corporations.