Costco, Target and Walmart all have big box and specialty stores.
But the Costco brand is the biggest, according to research firm Euromonitor International.
The study, conducted last month by consulting firm Retail Channel, found Costco was the second-largest brand overall and the fourth-largest by brand sales at 7.2% in 2018, according the report.
It’s up 3.3% from the year prior.
The Walmart brand was second with 4.7% sales growth, while Target and Costco were third with 3.7%, fourth with 2.4%, fifth with 2% and sixth with 1.5%.
The study also found that Costco is the fastest growing category with sales growth of 1.7%.
Kroger, a second-tier retailer that sells grocery, electronics and household goods, saw sales growth in 2018 of 2.9%, according to the report, which cited data from Kantar Worldpanel ComTech.
Kroger was fourth with 1% growth, and Target was fifth with 1%.
Walmart was the fastest growth category with 2%.
The research firm said the rise in sales for Costco and Target is due in part to a focus on the brand.
The companies have made significant investments in store development, marketing and customer service.
Costco said in October that it has built an additional 500 Costco locations in the United States, Canada and Puerto Rico.
Walmart has more than 8,000 stores in the U.S. and Canada.
In 2018, it had 4,100 stores and 3,000 employees, according data from the company.
Krog is expected to open 1,800 to 2,000 new U.K. and U.A.E. stores.