American financier who, as the third president of the International Bank for Reconstruction and Development (World Bank) (World Bank) from 1949 to 1962, expanded its membership and lent billions of dollars without a default.

Black, the son of a governor of the Federal Reserve Bank of Atlanta, graduated with honours from the University of Georgia (B.A., 1917) and served in the U.S. Navy during World War I before becoming a successful investment banker on Wall Street, specializing in the bond market. In 1947 he joined the World Bank as U.S. executive director for the United States under its second president, John J. McCloy, whom he succeeded two years later. Although the bank was originally formed in 1946 for the reconstruction of Europe after World War II, Black enlarged its scope, expanding the membership from 48 nations with a capital of $8.3 billion to 80 members with a capital of $20.5 billion. Black formed two bank affiliates—the International Development Association, which secured loans for developing countries, and the International Finance (International Finance Corporation) Corp., which promoted the private sector. Upon his resignation in 1962, he served as President Lyndon Johnson's emissary to Southeast Asia, helped lay the foundation for the creation of the Asian Development Bank, and held executive posts in many corporations and institutions.