Break up the Tech Giants

Google, Apple, Facebook, Amazon and Microsoft. In the space of just ten years, these five have become the biggest companies on the planet, each utterly dominating the market they operate in. They've got so large by offering consumers what they want but should we be worried about so much wealth and influence over our lives being centralised by a handful of tech giants on the west coast of America? Nik Gowing chairs a lively debate.