Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react as European stock markets open early June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HXAA

Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react as European stock markets open early June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce TPX IMAGES OF THE DAY - RTX2HXC3

A man gestures past a a screen displaying news of markets update inside the Bombay Stock Exchange (BSE) building in Mumbai, India, June 24, 2016. REUTERS/Danish Siddiqui - RTX2HXB8

People stand past a a screen displaying news of markets update inside the Bombay Stock Exchange (BSE) building in Mumbai, India, June 24, 2016. REUTERS/Danish Siddiqui - RTX2HXC6

A TV shows the resignation of Britain's Prime Minister David Cameron as traders from BGC, a global brokerage company in London's Canary Wharf financial centre react after European stock markets opened June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HXH7

Traders look at their screens at the stock exchange in Frankfurt, Germany, June 24, 2016, after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Ralph Orlowski - RTX2HXNH

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Ralph Orlowski - RTX2HXNM

A trader reacts at the stock exchange in Frankfurt, Germany, June 24, 2016, after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Ralph Orlowski - RTX2HXO2

An employee of a foreign exchange trading company works between a British flag and an EU flag in Tokyo, Japan, June 24, 2016. REUTERS/Issei Kato TPX IMAGES OF THE DAY - RTX2HXRM

Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react as European stock markets open early June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce

File Image: Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react during trading June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum.

A display shows the winners and losers at the Swiss Market Index (SMI) at the Swiss stock exchange in Zurich, Switzerland June 24, 2016. REUTERS/Arnd Wiegmann - RTX2HXVW

A trader from BGC, a global brokerage company in London's Canary Wharf financial centre reacts during trading June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HY02

A man walks past a screen displaying news of markets update inside the Bombay Stock Exchange (BSE) building in Mumbai, India, June 24, 2016. REUTERS/Danish Siddiqui - RTX2HXC5

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Staff/Remote - RTX2HXII

A traders reacts at the stock exchange in Frankfurt, Germany, June 24, 2016, after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Ralph Orlowski - RTX2HXNS

A cameraman takes pictures of a display showing a graphic of the Swiss Market Index (SMI) at the Swiss stock exchange in Zurich, Switzerland June 24, 2016.

A trader from BGC Partners, a global brokerage company in London's Canary Wharf financial centre waits for European stock markets to open early June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce TPX IMAGES OF THE DAY - RTX2HX5C

Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react as European stock markets open early June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HXLI

A man walks past a screen displaying market indices outside a brokerage in Tokyo, Japan, June 24, 2016. REUTERS/Thomas Peter - RTX2HXO4

Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react during trading June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HXU8

Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react as European stock markets open early June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HX9P

People look at a screen across a road displaying the Sensex on the facade of the Bombay Stock Exchange (BSE) building in Mumbai, India, June 24, 2016. REUTERS/Danish Siddiqui - RTX2HXD0

A man walks past a screen displaying market indices outside a brokerage in Tokyo, Japan, June 24, 2016. REUTERS/Thomas Peter - RTX2HXNN

Traders from BGC, a global brokerage company in London's Canary Wharf financial centre react during trading June 24, 2016 after Britain voted to leave the European Union in the EU BREXIT referendum. REUTERS/Russell Boyce - RTX2HXS8