GlaxoSmithKline plc (GSK) is a British multinational pharmaceutical, biologics, vaccines and consumer healthcare company headquartered in London, United Kingdom. It is the world's fourth-largest pharmaceutical company measured by 2009 prescription drug sales (after Pfizer, Novartis, and Sanofi). It was established in 2000 by the merger of Glaxo Wellcome plc (formed from the acquisition of Wellcome plc by Glaxo plc) and SmithKline Beecham plc (formed from the merger of Beecham plc and SmithKline Beckman Corporation, which was formed by combining the Smith Kline French and Beckman companies).

GSK has a portfolio of products for major disease areas including asthma, cancer, virus control, infections, mental health, diabetes and digestive conditions. It also has a large consumer healthcare division that produces and markets oral healthcare and nutritional products, drinks and over-the-counter medicines, including Sensodyne, Boost, Horlicks, Lucozade and Ribena.

In July 2012, GSK pleaded guilty to criminal charges and agreed to a $3 billion settlement of the largest health-care fraud case in the U.S. and the largest payment by a drug company in the US. The settlement was related to the company's illegal promotion of prescription drugs, its failure to report safety data, bribing doctors, and promoting medicines for uses for which they were not licensed.

GSK has a primary listing on the London Stock Exchange and is a constituent of the FTSE 100 Index. As of 6 July 2012, it had a market capitalisation of ?74.8 billion, the fifth-largest of any company listed on the London Stock Exchange. It has a secondary listing on the New York Stock Exchange.

(en.wikipedia)