American banker and financier who began his career by reorganizing corporations and went on to help establish financial stability in countries around the world.

Lamont graduated from Harvard University in 1892 and, after a brief stint on the financial desk of the New York Tribune, began working for Cushman Brothers Co., a New York food importer and exporter. The firm suffered financial problems, and Lamont came to its rescue with a reorganization plan and new capital, thus creating in 1898 the firm of Lamont, Corlis & Co. with his brother-in-law. Lamont's success earned him a reputation as a financial problem solver.

In 1903, when the Bankers Trust Co. was formed, Lamont was asked to be its secretary and treasurer by Henry P. Davison, who had been impressed with Lamont's handling of the Cushman reorganization. Within two years he was vice president of the new bank. Before leaving the bank in 1909, Lamont went to Europe for the American Bankers Association to establish an internationally accepted system of drafts known as travelers' checks. Two years later he became the youngest partner in the bank of J.P. Morgan, a relationship that he maintained until his death, serving for the last five years of his life as chairman of the board. In 1918 Lamont satisfied his lifelong fascination with journalism by purchasing the New York Evening Post, only to sell it four years later at a significant loss.

During World War I Lamont, with his friend Davison, arranged the financing and purchasing of supplies in the United States to be sent to France and England. After the war he negotiated reconstruction financing and the conditions for German reparations payments as a member of the American delegation to the Paris Peace Conference (1919) and as one of the participants in the drafting of the Dawes (1924) and Young (1929) plans. In the mid-1920s Lamont helped stabilize the French franc and the Italian lira by arranging $100 million lines of credit. After a devastating earthquake in Japan in 1923, he helped arrange a loan for that country for $250 million. He traveled annually to Europe, South America, and East Asia to help solve international monetary problems and consult with world and financial leaders.