I am seeing major retailers, ie Wal-Mart, Target, Sam's Club, etc. taking over Google Base listings in my sector. I used to have excellent rankings and traffic from G Base, but now it all seems to be favoring major brands. Anybody else seeing this swing?

We are the leading site for these products, but some of these other larger sites have recently been adding the products in my sector, so it's possible that this has been the norm for others.