Costco's CEO said the extended shopping hours for executive members boosted weekly sales by 1%.The wholesale club beat expectations with full-year revenue growth of 8.1%.Additional shopping hours also led more US members to upgrade to the executive tier.

Costco's move to extend operating hours this summer is paying off big.

"We estimate these incremental hours added about 1% to weekly US sales since implementation. This has been very well received by our members," CEO Ron Vachris said during the company's fourth quarter earnings call Thursday.

The company beat expectations with full-year revenue of $269.9 billion, or 8.1% over last year.

CFO Gary Millerchip also said that the extended hours and other new perks led a higher share of shoppers to upgrade their memberships.

Costco finished the quarter with 81 million paid memberships, of which 38.7 million were executive tier. Within the 1.4 million additional memberships, 1.1 million were executive.

Foot traffic data from Placer.ai indicates the adjustment is helping the company accomplish several key goals, namely getting shoppers to visit more quickly and more often.

"It's early, but I do think this is a win," Placer.ai analyst RJ Hottovy told Business Insider.

This is a developing story. Check back for updates.