The Big Six retailers are all Costco-owned and have about a 20% share of the overall US market.
The big players in terms of revenue share are Target, Wal-Mart, Amazon, Walmart and Costco.
The other big names in terms, like Wal-mart, are also all Costco brands.
Target, on the other hand, is owned by a smaller conglomerate and has a much smaller market share.
Walmart has a higher share of merchandise than the Big Six brands, but the retailer is losing ground to its competitor Amazon in terms that pertain to pricing.
Costco has a very good pricing model, but that’s because the company doesn’t have to compete with Amazon’s massive pricing.