Shares of Nabisco Group Holdings Corp. rose 2.6 percent Friday after a published report said R.J. Reynolds Tobacco Holdings Inc. is considering bidding for the successor to its former parent company.Nabisco Group, which owns 80.6 percent of the company that makes Ritz crackers and Oreo cookies, put itself and its investment in the snack business up for sale last month after shareholder Carl Icahn said he was prepared to boost his stake.