Nigerian President Muhammadu Buhari listens as British Prime Minister Cameron opens the international anti-corruption summit on May 12, 2016 in London, England. REUTERS/Dan Kitwood/Pool

An employee poses for photographs with Samsung Electronics' Galaxy Note 7 new smartphone at its store in Seoul, South Korea, September 2, 2016. REUTERS/Kim Hong-Ji/File Photo

An employee poses for photographs with Samsung Electronics' Galaxy Note 7 new smartphone at its store in Seoul, South Korea, September 2, 2016. REUTERS/Kim Hong-Ji/File Photo

A Wells Fargo branch is seen in the Chicago suburb of Evanston, Illinois, U.S. on February 10, 2015. REUTERS/Jim Young/File Photo

A sign for the headquarters of Valeant Pharmaceuticals International Inc is seen in Laval, Quebec June 14, 2016. REUTERS/Christinne Muschi

Cast members Lena Headey (L) and Emilia Clarke are shown in this combination photo at they attend the premiere for the sixth season of HBO's "Game of Thrones" in Los Angeles April 10,, 2016. REUTERS/Phil McCarten/File Photos

Cast members Sophie Turner (L) and Maisie Williams are shown in this combination photo at they attend the premiere for the sixth season of HBO's "Game of Thrones" in Los Angeles April 10,, 2016. REUTERS/Phil McCarten/File Photos

Cast members Maisie Williams and Sophie Turner arrive for the season four premiere of the HBO series "Game of Thrones" in New York March 18, 2014. REUTERS/Lucas Jackson/File Photo