E-commerce giant Coupang posted a drop in sales reflecting customer concerns over the company's insufficient handling of a massive data breach that affected more than 33 million people.

According to data from the Financial Supervisory Service obtained by the office of minor Rebuilding Korea Party Rep. Cha Gyu-geun on Wednesday, Coupang reported a seven-percent drop in its daily average sales.

The daily average of authorized payment of 78-point-seven billion won, or around 54 million U.S. dollars, between November 1 and 19, before the data breach was announced, fell seven-point-11 percent to 73-point-one billion won between November 20 and December 31.

The daily average number of approved payments during the same period dropped seven-point-07 percent from two-point-53 million to two-point-35 million.

The daily average payment in December, which normally increases due to rising year-end demand, fell five-point-16 percent compared to the previous month.