The decision of the UK to leave the EU imposes a key challenge for trade relations; regardless of the outcome of trade talks, trade costs are set to increase with the resulting shocks more severe for goods that are highly dependent on few suppliers. In the worst case scenario, say Lisandra Flach (EconPol Europe, LMU Munich and ifo Institute) and Feodora Teti (EconPol Europe, LMU Munich and ifo Institute), these shocks will cause significant supply chain disruptions that will have a much harsher impact on the UK than any EU member state.These product dependencies, they say, emphasize the need for a trade agreement that minimizes the costs of Brexit for both sides and reduces the uncertainty in international relations.