State Bank of India is the largest state-owned banking and financial services company with its headquartered in Mumbai, India. The bank traces its ancestry to British India, through the Imperial Bank of India, to the founding in 1806 of the Bank of Calcutta, making it the oldest commercial bank in the Indian Subcontinent. Bank of Madras merged into the other two presidency banks, Bank of Calcutta and Bank of Bombay to form Imperial Bank of India, which in turn became State Bank of India. The government of India nationalized the Imperial Bank of India in 1955, with the Reserve Bank of India taking a 60% stake, and renamed it the State Bank of India. In 2008, the government took over the stake held by the Reserve Bank of India.