GlaxoSmithKline plc (GSK) is a British pharmaceutical company headquartered in Brentford, London. Established in 2000 by a merger of Glaxo Wellcome and SmithKline Beecham, GSK was the world's sixth largest pharmaceutical company as of 2015, after Pfizer, Novartis, Merck, Hoffmann-La Roche and Sanofi. Emma Walmsley became CEO on 31 March 2017 and is the first female CEO of the company.
The company has a primary listing on the London Stock Exchange and is a constituent of the FTSE 100 Index. As of August 2016 it had a market capitalisation of £81 billion (around $107 billion), the fourth largest on the London Stock Exchange. It has a secondary listing on the New York Stock Exchange.
GSK's drugs and vaccines earned £21.3 billion in 2013. Its top-selling products that year were Advair, Avodart, Flovent, Augmentin, Lovaza and Lamictal. GSK's consumer products, which earned £5.2 billion in 2013, include Sensodyne and Aquafresh toothpaste, the malted-milk drink Horlicks, Abreva for cold sores, Breathe Right nasal strips, Nicoderm and Nicorette nicotine replacements, and Night Nurse, a cold remedy. The company developed the first malaria vaccine, RTS,S, which it said in 2014 it would make available for five percent above cost. Legacy products developed at GSK include several listed in the World Health Organization Model List of Essential Medicines, such as amoxicillin, mercaptopurine, pyrimethamine and zidovudine.