No that is not anti-competitive, because Wal-Mart isn't a platform that lets other companies sell through their stores. Wal-mart is notorious for using it's buying power to push down the purchase prices for it's inventory.

This type of question has already been answered. Are you aware of what sea-lioning is?

So Walmart isn’t a “platform” even though they sell goods from third parties but Amazon is a platform that sells goods from third parties? What’s the difference?