Shearman & Sterling has joined Allen & Overy, Clifford Chance and Herbert Smith Freehills on the agreement between Liberty Global and Telefónica to merge their U.K. operations bringing together Virgin Media and O2 in a 50-50 joint venture.

The transaction is expected to allow for a £10 billion investment into the U.K across the next five years, and will create a £31 billion media and telecoms giant. O2 is the U.K.’s largest mobile platform, while Virgin Media is the fastest broadband network.