Walmart is currently in third place in terms of number of retail clinics, eclipsed by Walgreens and CVS. However that statistic fails to take into account that all Walgreens stores and all CVS stores are obviously drug stores, while not every Walmart has a pharmacy. Kalorama Information's report on retail clinics: Retail Clinics 2011: Growth of Stores, Best Venues, Winning Competitors, Supplier Sales of Products to Clinics, Clinic Sales Forecasts and Trends has concluded that drug stores are the most viable locations.
When we look at percentage of retail clinics in drug stores, we can see that Walgreens is far in the lead and Walmart is only slightly behind (seven-tenths of a percent) CVS. They are operating in the zone of competition now with the two giants. Of course, time will tell if this commitment to stores continues.