GlaxoSmithKline (GSK) is a global pharmaceutical company headquartered in London. It has a portfolio of products for major disease areas such as asthma, cancer, infections and mental health. GSK was formed in 2000 through the merger of Glaxo Wellcome and SmithKline Beecham. It has operations in over 120 countries and sells products in over 150 countries. Its top competitors include Johnson & Johnson, Pfizer, Merck and AstraZeneca.