sentences:  He is first recorded as joining the famous Medici bank in either 1438 or 1439 (at seventeen or eighteen years of age) as a factor to the Avignon branch, employed by Cosimo de' Medici.His rise was remarkably quick, and he became a junior partner in that branch, and then its general manager, investing his own money in the branch and receiving a share of the profits.By 1453, he had been transferred to the Geneva branch (which as before, he invested in—though he maintained his investment in the Avignon branch), and in 1458 had returned home to Florence to a position as an adviser to Piero and Lorenzo de' Medici (who had succeeded Cosimo); he also married.