William Lynch resigned Monday as chief executive of struggling US bookseller Barnes & Noble, which has seen its Nook tablet fail to attract the hordes of readers who are shifting to digital books. Lynch\'s departure was part of a management shake-up at the New York City-based company. Changes included appointing Michael Huseby as chief of Nook Media and president of Barnes & Noble. \"As the bookselling industry continues to undergo significant transformation, we believe that Michael (Huseby), Mitchell (Klipper) and Max (Roberts) are the right executives to lead us into the future,\" board chairman Leonard Riggio said in a release. Huseby was hired as chief financial officer at Barnes & Noble early last year, while Lynch served as chief for about three years. The bookseller said in June that it was planning a new partnership for its Nook tablet computers in the face of ongoing losses at the division. The Nook segment, which includes devices, digital content and accessories, posted an operating loss of $177 million in the past quarter, as sales of the tablet fell in an intensely competitive market. The Nook has failed to make headway in a fast-growing tablet market dominated by the Apple line of iPads, and a handful of manufacturers using the Google Android operating system including Amazon\'s Kindle and Samsung\'s Galaxy Tab. Overall, B&N, including its subsidiary units, posted a quarterly loss of $118.6 million, on revenues of $1.3 billion. Shares in the company slid 17 percent to close at $15.61.