The director of the Centers for Disease Control and Prevention abruptly resigned Wednesday, following a report she bought shares in a tobacco company after she took the reins of the top U.S. public health agency. Brenda Fitzgerald’s resignation came after just six months on the job and after Politico reported that she purchased up to $15,000 of shares in Japan Tobacco. As CDC director, Fitzgerald also bought shares in pharmaceutical and healthcare companies that critics say posed potential conflicts of interest.