European stocks slipped into negative territory by midday Thursday as softer inflation data in Germany and Spain weakened the euro and concerns over the strident tone of Brexit negotiations.
British and international banks are able to operate across all countries in the European Union without holding individual regulatory permissions. That may change.
Banks and other institutions from the U.S and further afield arguably face the greatest difficulty.
U.K. stock markets were boosted by dollar earners while continental stocks also enjoyed a boost after what was seen as a conciliatory speech from Prime Minister Theresa May.