This document discusses the risks to London's financial services sector from the UK's exit from the EU. It notes that London is Europe's financial hub and a leading global center, and that EU membership has provided two key advantages - access to skilled migrant workers and passporting rights allowing UK firms to operate across the EU single market. Brexit puts both of these at risk. Losing passporting could force major restructuring of operations and cost the sector billions. Uncertainty over immigration policy may also deter EU talent. While opportunities exist in developing new markets and fintech, protecting access to the EU single market is viewed as critical for London to maintain its role as a top global financial center.