GlaxoSmithKline plc (GSK) is a British multinational pharmaceutical company headquartered in London, England.[4] Established in 2000 by a merger of Glaxo Wellcome and SmithKline Beecham,[n 1] GSK was the world’s sixth largest pharmaceutical company according to Forbes as of 2019, after Pfizer, Novartis, Roche, Sanofi, and Merck & Co.[5] GSK is the tenth largest pharmaceutical company and on the 2019 Fortune 500, ranked behind other pharmaceutical companies including China Resources, Johnson & Johnson, Roche, Sinopharm, Pfizer, Novartis, Bayer, Merck, and Sanofi