Following the failure of Morris Ketchum & Son in 1864 and the discovery of a vast embezzlement scheme by the son of Fourth National Bank of New York president Morris Ketchum, Calhoun was asked to take over as president of the Bank when "the Directors of the bank and several of its largest stockholders went to Bridgeport and urged him to accept the position, and, at great personal sacrifice, he acceded to their request."