Starbucks' stock continued to slump Friday after the coffee chain posted another quarter of disappointing sales growth on Thursday and blamed holiday offerings for failing to draw in customers.

Shares of the coffee giant were down nearly 5 percent in midday trading as investors question if the company can revitalize sales in the U.S.

Although same-store sales came up short in all of Starbucks' regions, save for strong growth in China, investors have been focused on weak U.S. results. U.S. same-store sales grew 2 percent in the quarter, with the poor sales of holiday beverages, merchandise and gift cards a big factor.

"Our holiday merchandise that we had did not perform up to our expectations," CEO Kevin Johnson said on CNBC's "Squawk on the Street" Friday. "That's not anything to do with the core execution of the company."

Same-store sales in the U.S. could have been more than a percentage point higher if not for this weakness, he said.