He was a freed African-American Muslim slave who later became one of the first shareholders of the second chartered bank in America, the Columbia Bank Yarrow Mamout was a freed African-American Muslim slave who later became one of the first shareholders of the second chartered bank in America, the Columbia Bank. Enslaved at 16, Mamout spent 44 years as a slave before he was freed at 60, living in Georgetown. He was described as “a jack of all trades”, making money by making charcoal, loading ships, and weaving baskets. As he rose in financial standing, he acquired property of his own, and became a financier who lent money to merchants.