The leading investment banks have many reasons to worry ahead of 2017 and 2018 fiscal years, that’s when the U.K. could complete its retreat from the European Union formalities, potentially revealing the full scope of consequences for lenders entrenched in London.

The European banks should consider the pact together on the Federal Reserve’s annual stress tests to elude having a portion of their profits sheltered across the Atlantic.

The Fed’s latest assessments of whether banks can withstand a financial crisis come on Wednesday.

The U.S. units of Deutsche Bank AG and Banco Santander SA were the only firms of 31 tested that failed in 2015.

While some foreign banks could again fall short this week, that kind of floundering will have a much greater impact two years from now.

Stress Tests Flunk Banks to Build Confidence in Them: QuickTake

“The whole foreign-bank process is going to be a little bumpy for a while,” said Oliver Ireland, a partner with law firm Morrison & Foerster in Washington.

Things are likely to take a shift in 2017 and in 2018 when the Fed begins with weighing the U.S. business of every major foreign bank in its entirety, bringing in firms such as Credit Suisse Group AG, Barclays Plc and UBS Group AG for the first time.

After next year’s financial trials, foreign banks’ results would instigate to really matter in 2018, the first time they’ll be made public. A failing grade permits the Fed to block a firm from sending billions of dollars in revenue back to their European parents.

The stakes will be even higher as lenders look to the U.S. to help offset profits they could lose in the U.K. following voters’ surprise decision last week to withdraw from the EU. Analysts at JPMorgan Chase & Co. estimated that Brexit might trigger a 20 pct earnings hit for banks exposed to the U.K., with a 17 pct impact on pretax profit at Deutsche Bank and 21 pct at Credit Suisse.

Why do we think hedging further GBP depreciation: In this course of action, we forecast pound sterling likely to tumble even lower levels. Further into 2016, there are two key risks for GBP – namely, the UK’s unsustainable current account deficit and the risks associated with formalities of dissolution of EU membership, promised for end-2017 at the earliest 2018 at the latest.

We think both are manageable, however, and the current account may actually strengthen the case for GBP outperformance from here on.

But we have argued for some time that the UK’s external deficit is largely a public sector phenomenon and this is still true but is becoming less so as the household sector slips into deficit. As this happens, the policy prescription is slowly shifting to tighter monetary and fiscal policy rather than fiscal policy alone.