This Practice Note explores the network and facilities sharing arrangements entered into by mobile network operators (MNOs). In examining the key types of infrastructure sharing, the strategic rationale behind the practice, infrastructure sharing models, competition issues, and future developments, it presents an overview of how legal and regulatory risks may be best managed in the UK market. Navigating the complex waters of negotiating network and facilities sharing arrangements can bring significant benefits for MNOs. Strategic sharing initiatives continue to present significant cost saving opportunities, whether collaborating with market competitors, or through tie-ups with independent tower companies or facilities providers. However, as this Practice Note illustrates, it remains key to ensure that inherent legal and regulatory risks are managed effectively when negotiating and concluding arrangements. Brexit This Practice Note focuses on the position in the UK market and includes consideration of relevant UK competition law. This primarily focuses on the block exemptions which may be applicable to the type of sharing arrangements discussed here. Block exemptions specify conditions under which certain types of