Mike Adenuga

Mike Adenuga, Nigeria's second richest person, built his fortune in telecommunications and oil production.

His mobile phone network, Globacom, is the third-largest operator in Nigeria, with more than 17 million subscribers.

His oil exploration outfit, Conoil Producing, operates 6 oil blocks in the Niger Delta.

Globacom also built Glo-1, a 6,100-mile-long submarine Internet cable to the U.K. via Ghana and Portugal.

Adenuga also owns 74% of publicly traded gasoline firm Conoil and just under 6% of publicly traded Nigerian bank Sterling Financial Holding.

Adenuga got an MBA at Pace University in New York, supporting himself as a student by working as a taxi driver.

Adenuga made his first million at age 26 selling lace and distributing soft drinks.