O2 (UK) 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 Securicor's share of Cellnet and the company was later rebranded as BT Cellnet. In June 2000, BT Cellnet launched the world's
Power Corporation of Canada in 2000 with the acquisition of Canada Life, Mackenzie Financial and Putnam Investments. Power Corporation owns 100% of Square Victoria Communications Group and 65.6% of Power Financial Corporation. While it was originally established as an electric utility holding company, the company became a conglomerate with major interests in the finance industry, as well as interests in other business sectors such as communications and renewable energy. The Co-Chief Executive Officers are Paul Desmarais, Jr. and André Desmarais. As a holding company, the officers run the companies through the various Boards. Responsible management has long been a corporate value at Power Corporation.