Costco (COST -0.14%) has continued accelerating its sales rebound since comparable-store sales dipped in April during the height of the COVID-19 U.S. stay-at-home orders and store closures. The big-box retailer reported net monthly June sales of $16.18 billion, an increase of 11.1% over the prior-year period. The sales gains were higher than the 5.4% same-store sales increase in May 2020. 

As earlier lockdown measures were implemented in an attempt to contain the spread of the COVID-19 pandemic, Costco reported its first decline of same-store sales in over a decade in April 2020. Sales growth rebounded in May, and the pace has accelerated in June. 

A shopper in a big-box retail store pushes a cart.

Image source: Getty Images.

E-commerce sales have continued to lead the sales resurgence. The company reported June e-commerce sales jumped 86%, following a 106% rise in May, versus 2019.

David Sherwood, assistant vice president of finance and investor relations, said in a recorded message that merchandise sales were very strong, but ancillary areas were mixed in June. He said that optical and hearing aid sales "improved significantly from May," as those departments reopened. He noted that softness continued in gas, food court, and photo sales. Foot traffic has been increasing in the U.S., he said, as June marked the first positive result since March. 

Costco currently operates 788 warehouses, almost 70% of which are in the U.S., including Puerto Rico. The other leading geographic locations are Canada, Mexico, the U.K., and Japan. The retailer opened its first store in Shanghai, China in August 2019.