European banking shares fell following Donald Trump's victory in the race to the White House, with valuations wilting on concerns ranging from Chinese and Mexican exposure to the sector's unfinished business with U.S. regulators.

Spanish banks BBVA (BBVA and Santander (SAN - Get Report)  , which both have significant operations in Mexico, were among the first to topple, and were down nearly 10% each in early trade. Italian banks also plunged, with Banca Monte dei Paschi (BMDPY recently down almost 6% on concern market uncertainty following Trump's victory could jeopardize a rescue rights issue worth up to €5 billion ($5.6 billion). UniCredit was recently down 2.8%.

 HSBC (HSBC , Natixis (NTXFF , Deutsche Bank (DB - Get Report) , Barclays (BCS and RBS (RBS also came under pressure.

HSBC was among the biggest fallers in the London banking sector on Wednesday. The stock fell by around 3% after the opening bell and was down by around 1.8% in mid-morning trading, at 611.2 pence ($7.63). The SSE Composite, China's benchmark domestic stock index, fell by nearly 2% during the Asia session but eventually closed 0.6% lower at 3,128.4.

HSBC is heavily exposed to China,  a nation that could face economic pressures as a result of Trump's victory, after the soon-to-be 45th U.S. president threatened to designate the world's second- largest economy as a currency manipulator and apply heavy tariffs to imports from the nation.

Deutsche Bank stock was among the biggest fallers on the DAX. The German bank's stock was down more than 5% shortly after the opening bell, to touch lows of €12.21 ($13.43), as investors fretted about the prospect of U.S. authorities taking a harder line on misconduct by foreign banks under Trump's leadership.

The Department of Justice in September threatened to fine it  $14 billion over the sale of mortgage-backed securities during the financial crisis.

RBS and Barclays also fell sharply.

Barclays stock fell by as much as 5%, to reach a low point of 176.0 pence, after the opening bell. RBS stock fell more than 3% to reach a session low of 180.6 pence.

Also among the big losers for the European banking sector were big dollar earners, such as France's Natixis (NTXFF , who faces an €80 million hit to operating profits for every 10 cents movement in the dollar-euro exchange rate, according to analysts at Jefferies.

The dollar was initially down 3 cents against the euro.

Natixis shares were down more than 9% in early trade, touching a session-long low of €4.19, before paring losses.