"Our taxpayers bear the risk, so it would be unrealistic for us to implement new EU legislation automatically and in its entirety."
In her speech today, May said: "The UK has responsibility for the financial stability of the world’s most significant financial centre, and our taxpayers bear the risk, so it would be unrealistic for us to implement new EU legislation automatically and in its entirety.
"Our goal should be to establish the ability to access each others’ markets, based on the UK and EU maintaining the same regulatory outcomes over time, with a mechanism for determining proportionate consequences where they are not maintained."
She added that chancellor Philip Hammond will outline next week how financial services should form a "deep and comprehensive partnership".
Passporting rights enable UK financial services firms to sell services without restriction across the EU.
FCA data for 2016 shows that almost five and a half thousand UK firms are using passports to do business in Europe, and over eight thousand European firms are using passports to provide services in the UK.
Former chairman of the Treasury Committee, Andrew Tyrie, said the figures "give us an initial idea of the effects of losing full access to the single market in financial services".
Tyrie added: “The business put at risk could be significant. None of the current off-the-shelf arrangements can preserve existing passporting arrangements, while giving the UK the influence and control it needs over financial services regulation as it develops. Efforts to secure an appropriate arrangement for UK-based firms will be one of the most challenging aspects of the negotiations about the UK’s future relationship with the EU."
