 His parents were dry goods merchants and he had one older brother, Julius, and one younger sister, Ella.In 1893, Loeb graduated from gymnasium and moved to New York City to work with his brother at the American Metal Company (AMCO), a lead and zinc trader and subsidiary of Metallgesellschaft AG (founded by Wilhelm Ralph Merton, Leo Ellinger, and Zachary Hochschild).In 1893, he moved to St. Louis to assist at a branch office (and also met his future wife) and was promoted to branch manager after convincing then AMCO president Jacob Langeloth that he could handle the responsibility despite being only 21.