Traders walk on the floor of the Borsa Istanbul in Istanbul, Turkey February 29, 2016. REUTERS/Murad Sezer

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, March 3, 2016. REUTERS/Staff 

A trader passes by a screen displaying the trading info for Intercontinental Exchange Inc. (ICE) on the floor of the New York Stock Exchange (NYSE) March 1, 2016. REUTERS/Brendan McDermid

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 25, 2016. REUTERS/Staff/Remote 

Traders work on the floor of the New York Stock Exchange (NYSE) February 24, 2016. REUTERS/Brendan McDermid

A trader works by the post where JPMorgan Chase & Co is traded on the floor of New York Stock Exchange (NYSE) February 24, 2016. REUTERS/Brendan McDermid

Traders work by the post where JPMorgan Chase & Co is traded on the floor of New York Stock Exchange (NYSE) February 24, 2016. REUTERS/Brendan McDermid

The German share prize index (DAX) board and the trading room of Frankfurt's stock exchange (Boerse Frankfurt) are photographed with a circular fisheye lens during afternoon trading session in Frankfurt, Germany, February 23, 2016. REUTERS/Kai Pfaffenbach TPX IMAGES OF THE DAY

The ticker symbol for Fitbit is displayed at the post where it is traded on the floor of the New York Stock Exchange (NYSE) February 23, 2016. REUTERS/Brendan McDermid

The ticker symbol for United Technologies is displayed at the post where it is traded on the floor of the New York Stock Exchange (NYSE) February 23, 2016. REUTERS/Brendan McDermid

The ticker symbol for United Technologies is displayed at the post where it is traded on the floor of the New York Stock Exchange (NYSE) February 23, 2016. REUTERS/Brendan McDermid

The German share prize index (DAX) board and the trading room of Frankfurt's stock exchange (Boerse Frankfurt) are photographed during afternoon trading session in Frankfurt, Germany, February 23, 2016. REUTERS/Kai Pfaffenbach

The German share prize index (DAX) board and the trading room of Frankfurt's stock exchange (Boerse Frankfurt) are photographed with a circular fisheye lens during afternoon trading session in Frankfurt, Germany, February 23, 2016. REUTERS/Kai Pfaffenbach

The German share prize index (DAX) board and the trading room of Frankfurt's stock exchange (Boerse Frankfurt) are photographed during afternoon trading session in Frankfurt, Germany, February 23, 2016. REUTERS/Kai Pfaffenbach

The German share prize index (DAX) board is seen at the trading room of Frankfurt's stock exchange (Boerse Frankfurt) during afternoon trading session in Frankfurt, Germany, February 23, 2016. REUTERS/Kai Pfaffenbach

The German share prize index (DAX) board is seen at the trading room of Frankfurt's stock exchange (Boerse Frankfurt) during afternoon trading session in Frankfurt Germany, February 23, 2016. REUTERS/Kai Pfaffenbach

The trading room of Frankfurt's stock exchange (Boerse Frankfurt) is reflected in the window of the visitor's gallery during afternoon trading session in Frankfurt Germany, February 23, 2016. REUTERS/Kai Pfaffenbach

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 16, 2016. REUTERS/Staff/remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 16, 2016. REUTERS/Staff/remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 15, 2016. REUTERS/Staff 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 11, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 11, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 3, 2016. REUTERS/Staff 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, February 1, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 28, 2016. REUTERS/Staff/Remote 

Pedestrians walk past an electronic stock quotation board outside a brokerage in Tokyo, Japan January 22, 2016. Japan's Nikkei share average scored its biggest single-day gain in 4-1/2 months on Friday, helped by a weaker yen, a bounce in oil prices and a hint of more stimulus from ECB president Mario Draghi. REUTERS/Toru Hanai

A man (3rd L) looks at an electronic stock quotation board as passers-by walk past, outside a brokerage in Tokyo, Japan January 20, 2016. Japan's benchmark Nikkei share average tumbled to a fresh 14-1/2 month low on Wednesday as global markets were battered by plunging crude prices that slid to nearly $27 a barrel in the U.S. REUTERS/Toru Hanai

A man looks at an electronic stock quotation board outside a brokerage in Tokyo, Japan January 20, 2016. Japan's benchmark Nikkei share average tumbled to a fresh 14-1/2 month low on Wednesday as global markets were battered by plunging crude prices that slid to nearly $27 a barrel in the U.S. REUTERS/Toru Hanai

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 18, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 14, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 14, 2016. REUTERS/Staff/Remote 

People are reflected in a stock quotation board outside a brokerage in Tokyo, Japan January 14, 2016. Asian shares skidded on Thursday in the wake of steep losses on Wall Street, while a rout in oil and commodities prices, with crude plumbing 12-year lows, heightened fears about the global economy. REUTERS/Toru Hanai

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 8, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 8, 2016. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 7, 2016. European shares fell sharply on Thursday after China accelerated the depreciation of the yuan, sending currencies across the region reeling and domestic stock markets tumbling. REUTERS/Staff/Remote 

Traders work at their desks in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, January 7, 2016. European shares fell sharply on Thursday after China accelerated the depreciation of the yuan, sending currencies across the region reeling and domestic stock markets tumbling. REUTERS/Staff/Remote 

A worker sweeps the floor in front of the final stock price index as employees of the Korea Exchange (KRX) leave after the ceremonial closing event of the 2015 stock market in Seoul, South Korea, December 30, 2015. REUTERS/Kim Hong-Ji 

Workers sweep the floor in front of the final stock price index after the ceremonial closing event of the 2015 stock market at the Korea Exchange (KRX) in Seoul, South Korea, December 30, 2015. REUTERS/Kim Hong-Ji 

Employees of the Korea Exchange (KRX) pose in front of the final stock price index during a photo opportunity for the media at the ceremonial closing event of the 2015 stock market in Seoul, South Korea, December 30, 2015. REUTERS/Kim Hong-Ji 

Employees of the Korea Exchange (KRX) pose in front of the final stock price index during a photo opportunity for the media at the ceremonial closing event of the 2015 stock market in Seoul, South Korea, December 30, 2015. REUTERS/Kim Hong-Ji 

Traders are pictured at their desks in front of the DAX board at the stock exchange in Frankfurt, Germany, December 2, 2015. REUTERS/Staff/Remote 

The ticker information for Valeant Pharmaceuticals International Inc. is displayed on a screen above the post where it's traded on the floor of the New York Stock Exchange November 4, 2015. REUTERS/Brendan McDermid

The ticker information for Twitter Inc., is displayed on a screen above the post where it's traded on the floor of the New York Stock Exchange November 4, 2015. REUTERS/Brendan McDermid

The ticker information for Pfizer is displayed on a screen above the post where it's traded on the floor of the New York Stock Exchange November 4, 2015. REUTERS/Brendan McDermid

The ticker information for insurance company American International Group Inc., (AIG) is displayed on a screen above the post where it is traded on the floor of the New York Stock Exchange November 4, 2015. REUTERS/Brendan McDermid

Specialist trader Peter Giacchi reopens the stock for GNC Holding Inc. on the floor of the New York Stock Exchange October 22, 2015. Nutritional supplement retailer GNC Holding Inc knowingly sold products spiked with two synthetic drugs, Oregon's attorney general has charged, USA Today reported on Thursday, citing internal company records and a lawsuit. REUTERS/Brendan McDermid

Traders work on the floor of the New York Stock Exchange October 22, 2015. REUTERS/Brendan McDermid

A screen displays the Dow Jones Industrial Average after the closing bell on the floor of the New York Stock Exchange October 22, 2015. REUTERS/Brendan McDermid

A screen displays the Dow Jones Industrial Average after the closing bell on the floor of the New York Stock Exchange October 22, 2015. REUTERS/Brendan McDermid

Specialist trader Peter Giacchi reopens the stock for GNC Holding Inc. on the floor of the New York Stock Exchange October 22, 2015. Nutritional supplement retailer GNC Holding Inc knowingly sold products spiked with two synthetic drugs, Oregon's attorney general has charged, USA Today reported on Thursday, citing internal company records and a lawsuit. REUTERS/Brendan McDermid

Specialist trader Peter Giacchi reopens the stock for GNC Holding Inc. on the floor of the New York Stock Exchange October 22, 2015. Nutritional supplement retailer GNC Holding Inc knowingly sold products spiked with two synthetic drugs, Oregon's attorney general has charged, USA Today reported on Thursday, citing internal company records and a lawsuit. REUTERS/Brendan McDermid TPX IMAGES OF THE DAY

Traders work at their screens in front of the German share price index, DAX board, at the stock exchange in Frankfurt, Germany, October 19, 2015. REUTERS/Staff/remote 

Traders are pictured at their desks in front of the DAX board at the stock exchange in Frankfurt, Germany, October 5, 2015. REUTERS/Staff/remote 

Traders are pictured at their desks in front of the DAX board at the stock exchange in Frankfurt, Germany, October 5, 2015. REUTERS/Staff/remote 

Passersby are reflected on a stock quotation board at a brokerage in Tokyo, Japan, September 29, 2015. Asian shares skidded to 3-1/2-year lows and the dollar sagged on Tuesday, pulled down by a sharp losses on Wall Street after weak Chinese data rekindled worries about its fragile economy. REUTERS/Issei Kato TPX IMAGES OF THE DAY

Traders are pictured at their desks in front of the DAX board at the stock exchange in Frankfurt, Germany, September 24, 2015. REUTERS/Staff/remote 

Traders are pictured at their desks in front of the DAX board at the stock exchange in Frankfurt, Germany, September 24, 2015. REUTERS/Staff/remote 

Traders are pictured at their desks in front of the DAX board at the stock exchange in Frankfurt, Germany, September 18, 2015. REUTERS/Staff/remote 

An investor stands in front of an electronic board showing stock information at a brokerage house in Beijing, China, September 15, 2015. China's major stock indexes fell more than 2 percent in early trade on Tuesday. REUTERS/Kim Kyung-Hoon 

An investor sits in front of an electronic board showing stock information at a brokerage house in Beijing, China, September 15, 2015. China's major stock indexes fell more than 2 percent in early trade on Tuesday. REUTERS/Kim Kyung-Hoon