Vodafone is in talks with Three about merging their UK businesses. It would mean the third and fourth largest mobile phone networks respectively combining to create a business with 27 million customers, larger than current leaders BT, EE and Virgin Media O2. The companies say it would accelerate the rollout of 5G and rural broadband. Any deal would be scrutinised by the Competition and Markets Authority (CMA). Reports suggest the two companies are hopeful of striking a deal by the end of the year. Regulators have previously opposed mergers that would reduce the number of networks in the UK. However, Vodafone has pointed to a recent report from communications regulator Ofcom which might suggest a new approach. It found that both Vodafone and Three had in recent years delivered returns on investments that were lower than the cost of the capital they used. Vodafone pairing with Three is just one potential tie-up in the UK. Other deals involving Virgin Media O2, TalkTalk and Sky have been speculated in recent months.