Wal-Mart ( WMT) and Federated Department Stores ( FD) said Monday that holiday sales may be disappointing. Wal-Mart said its December same-store sales were running at the low end of its expectations. However, the retailer added that it was counting on last-minute holiday shoppers to boost sales. Wal-Mart had forecast December same-store sales would be up 3% to 5%. Meanwhile, Federated, the parent of Macy's and Bloomingdale's, said its sales for the November-December period would likely miss its target of flat to down 2.5%. Federated also said it was difficult to forecast results because of an expected rise in sales in the final shopping days before Christmas and the postholiday sales period.