 WILMINGTON, Del.--BUSINESS WIRE--Labaton Sucharow, a nationally ranked shareholder rights firm, is investigating potential securities violations and breach of fiduciary duty claims against drywall and joint compound company USG Corporation Former NYSE: USG in connection with its merger with Gebr. Knauf KG. If you are a former shareholder of USG and want to receive additional information and protect your investments free of charge, please contact David J. Schwartz using the toll free number 