A proposal that could force systemic foreign clearing houses with operations in the the European Union to relocate to the bloc if they want to continue servicing their EU clients has been backed by EU governments.

Based on a proposal made by the European Commission last year, the decision could have repercussions for US businesses and British clearing firms after Britain leaves the EU in March 2019.

As reported by the Reuters news agency, the text, if adopted in talks with EU lawmakers which will follow in the coming weeks, could concern LCH, a unit of the London Stock Exchange, which dominates clearing of euro-denominated interest rate swaps and after Brexit will be outside the EU. The move could strip London of a chunk of that business.

If, “as a measure of last resort and on the basis of a fully reasoned assessment”, the European Securities and Markets Authority (ESMA) decided that a foreign clearing house is of systemic importance for the bloc’s financial stability, it could force that firm “to establish itself in the EU in order to be able to operate,” the EU document said.

Also, Large US clearers such as CME and ICE could be affected by the new rules.