<Tr> <Th> Headquarters </Th> <Td> Bombay, Bombay State, India </Td> </Tr> <Tr> <Th> Area served </Th> <Td> India </Td> </Tr> <P> The Imperial Bank of India (IBI) was the oldest and the largest commercial bank of the Indian subcontinent, and was subsequently transformed into State Bank of India in 1955 . </P> <P> The Imperial Bank of India came into existence on 27 January 1921 by J.M. Keynes . When the three Presidency Banks of colonial India, were reorganised and amalgamated to form a single banking entity . The three Presidency banks were the Bank of Bengal, established on 2 June 1806, the Bank of Bombay (incorporated on 15 April 1840) and the Bank of Madras (incorporated on 1 July 1843) </P>

When was imperial bank was changed as sbi