Union Bank is a large commercial bank, serving individuals, small and medium-sized companies, as well as large corporations and organizations. In July 2009, it was rated the 556th largest bank in the world and the 14th largest bank in Africa. As of Mar 31, 2018, the bank's asset base was estimated at NGN1, 381 billion (US$4.1billion). The shareholders' equity at that time was estimated at NGN286 billion (US$851 million). The bank's history can be traced to 1836 when London bankers and British merchants obtained a royal charter from William IV to conduct banking business in the Caribbean. These group of investors then formed Colonial Bank. Following an act of parliament empowering the bank to open more branches beyond the Caribbean, Colonial bank began operations in Nigeria in 1917. Operations started with banking centers in Lagos, Jos and Port-Harcourt. Further centers were opened in financially important areas, in 1918, the bank opened additional centers at Ebute-Metta, Onitsha, Iba