In 1937, Thiru.M. Ct. M. Chidambaram Chettyar established the Indian Overseas Bank (IOB) to encourage overseas banking and foreign exchange operations. IOB started up simultaneously at three branches, one each in Karaikudi, Madras, and Rangoon (Yangon). It quickly opened a branch in Penang, Kuala Lumpur (1937 or 1938), and another in Singapore (1937 or 1941). The bank served the Nattukottai Chettiars, who were a mercantile class that at the time had spread from Chettinad in Tamil Nadu state to Ceylon (Sri Lanka), Burma (Myanmar), Malaya, Singapore, Java, Sumatra, and Saigon. As a result, from the beginning IOB specialised in foreign exchange and overseas banking.
Today, Indian Overseas Bank (IOB) is a major public sector bank based in Chennai (Madras), with about 3700 domestic branches, including 1150 branches in Tamil Nadu, 3 extension counters, and eight branches and offices overseas as of 30 September 2014. Indian Overseas Bank has an ISO certified in-house Information Technology department, which had developed the software that its branches used to provide online banking to customers earlier.The bank has achieved 100% networking status as well as 100% CBS status for its branches. IOB also has a network of about 3300 ATMs all over India.The bank has taken a late leap towards internet-enabled banking and data analytics by implementing Infosys Finacle's latest rack of software executed by American technology company HPE and became the first public sector bank to get the latest digital banking software, Finacle 10 suite package from Infosys. IOB has branches in Singapore, Hong Kong, Colombo, Seoul, and Bangkok. It has representative offices in Guangzhou, Vietnam, and Dubai. IOB also is part-owner of a joint-venture bank in Malaysia.