KPMG is one of the top four accounting firms in the world (the other three are Deloitte, PwC and RSM McGladrey) and a long-established professional accounting firm in Switzerland, providing audit, tax and advisory services to companies around the world. KPMG began as an accounting firm founded by William Barclay Pitt in London in 1870; it was merged in 1911 by William Barclay Pitt & Co. and Marwick Mitchell & Co. to form the current KPMG. The firm's administrative headquarters are in Amsterdam, the Netherlands. Its administrative headquarters are located in Amsterdam, the Netherlands, and its business headquarters are located in the United States.