Barnes & Noble CEO William Lynch has resigned, the struggling company announced after the market closed Monday. Lynch, who was appointed CEO in 2010, oversaw the brief rise and hasty decline of the company’s Nook business. Barnes & Noble is not appointing a new CEO to oversee the entire company; instead, the retail and digital sides will be managed separately. Michael Huseby, who was the company’s CFO, replaces Lynch as CEO of Nook Media and president of Barnes & Noble. Mitchell Klipper remains CEO of Barnes & Noble’s retail division. Huseby and Klipper will report to Barnes & Noble’s executive chairman and largest stockholder, Leonard Riggio. Max Roberts, CEO of Barnes & Noble’s college division, will report to Huseby. Allen Lindstrom, the company’s corporate controller, has been promoted to CFO to replace Huseby.