FAIRFIELD, PENNSYLVANIA— Quad unexpectedly closed all  its book printing operations, sending publishers scrambling to find a replacement. Quad put its book printing business up for sale last fall following the collapse of its proposed merger with the U.S. largest book printer, LSC Communications, after the U.S. Department of Justice filed an antitrust suit. Quad's  book printing division, acquired in 2010 as part of the World Color transaction, generates around $200 million in sales annually. It has facilities in Versailles, Kentucky, Fairfield, Pennsylvania and Martinsburg, West Virginia with around 1,350 full- and part-time employees. The closure comes at a time when the loss of printing capacity is one of the many concerns publishers are facing because of the Covid-19 . Quad is the second largest book printer in the United States.