TORONTO, Canada —  Shares of Hudson's Bay Co , the owner of luxury department store chain Saks Fifth Avenue, slumped more than 6 percent on Friday after the retailer reported disappointing quarterly same-store sales.

The department store operator joined Macy's Inc , Nordstrom Inc and other US-based retailers in posting weaker-than-expected same-store sales. The news pushed down department store stocks on Thursday and Friday.

"Despite management efforts to bring excitement back into the stores, traffic continues to shift away from the department store channel at an accelerating pace," Evercore ISI analyst Omar Saad said in a research note.

After markets closed on Thursday, Toronto-based Hudson's Bay said comparable store sales in all its brands fell 2.9 percent during the first quarter ended April 29, hurt by fewer customers shopping in its stores, particularly in the United States.

This fell short of estimates provided by two analysts who, on average, had forecast a decline of 1.2 percent, according to Thomson Reuters data.

Same-store sales at Saks fell 4.8 percent, a steeper decline than reported by Macy's, Nordstrom and J C Penney Co . Hudson's Bay's discount operations, Saks Off 5th and online website Gilt.com, fell 6.8 percent, a fifth straight decline.

The stock, which fell more than 8 percent at one point, was down 5.5 percent at C$10.10 at mid morning.

By Solarina Ho; editor: Bernadette Baum and Dan Grebler.