EU financial institutions (banking, insurance, savings, investments) have a regulatory passport system that allows regulated entities to operate across the EU, relying on the home countries licence to operate in all countries within the EU.

This means you do not always have to spend considerable funds and time in creating a local regulated entity and having a local licence just so you can sell products to EU consumers, or offer services to local companies. This is referred to as passporting by the FCA.

https://www.the-fca.org.uk/firms/passporting

The City of London is a financial service industry and the UK’s largest industry. The costs of administration for operating in the huge EU market are kept reasonable by passporting, as the EU rules allowed you to headquarter your entities and host your “front office” (the money making operations) in the City where they are surrounded by financial ancillary industries, infrastructure and services, and each of these is serviced by a host of other industries too, including catering, building maintenance and shops.

The multinationals will need to consider relocating front office to the EU. They simply cannot use their UK regulated entities to do business in the EU zone.

Middle and Back Office (who process trades) and building services staff will be made redundant, there is no cost or efficiency benefit to operating both a EU and UK/Rest of World trading hub, as it can be done by a single regulated entity within the EU. Frankfurt, Amsterdam, Paris and Dublin have the capability to cater to these large firms.

The City is essential to the financial health of the country, London’s financial industry generated £66.5bn in taxes during 2014/15. London itself has an economy the size of Sweden or Iran.

The workers generate billions of income taxes a year alone, and these workers provide considerable income to companies in their home towns around London and elsewhere in the UK. Their spending power and wealth is concentrating in the UK.

The Leave team presented no plan for the City and passporting.

As it stands the fast track Brexit proposed would mean the global financial institutions would have to decide and move quickly to continue trading in the EU.

The daily turnover of the City is trillions of pounds. In currency alone, in 2009 London processed $1.85 trillion A DAY in transactions, 39.7% of the entire global business, including more Euro transactions than every other city in Europe combined. This business will have to move to Europe. It cannot remain in London without the UK being in the EU or full access to the EEA.