O2 (UK) they can do it too" in reference to Vodafone and EE, O2's biggest competitors and the UK's top three mobile-telecoms companies. O2 (UK) Telefónica UK Limited (trading as O2 – stylised as O) is a telecommunications services provider in the United Kingdom, owned by the Spanish multinational Telefónica, and is headquartered in Slough. With 25 million subscribers (as of December 2017), O2 is the second-largest mobile network operator in the United Kingdom after EE, with Vodafone in third place. O2 was formed in 1985 as Cellnet, a 60:40 joint venture between BT Group and Securicor. In 1999, BT Group acquired
State Grid Corporation of China State Grid Corporation of China The State Grid Corporation of China (SGCC; ), commonly known as the State Grid, is the state-owned electric utility monopoly of China. It is the largest utility company in the world, and as of 2018, the world's second largest company overall by revenue. In 2016/17 it was reported as having 927,839 employees, 1.1 billion customers and revenue of 363.125 billion dollars. After the electricity "Plant-Grid Separation" reform in early 2002, the assets of State Electric Power Corporation (国家电力公司) were divided into the five "power generation groups" that retained the power plants and five regional subsidiaries