The NPD Group, Inc. acquired U.S. market information and research services for book industry unit from Nielsen Holdings plc (NYSE:NLSN) on January 20, 2017. Post acquisition, US book services unit will become part of NPD Book, a new entity. The NPD Group, Inc. completed the acquisition of U.S. market information and research services for book industry unit from Nielsen Holdings plc (NYSE:NLSN) on January 20, 2017.