John Sargent, CEO of Macmillan, will leave the publishing company and its parent, Holtzbrinck Publishing Group, on January 1. Don Weisberg, president of Macmillan US Trade, will succeed Sargent as CEO of Macmillan Publishers, and Susan Winslow, general manager of Macmillan Learning, will head that division as president. In making the announcement on September 17, Holtzbrinck said Sargent’s departure is due to “disagreements regarding the direction of Macmillan.”