Industry stalwarts Wal-mart Stores Inc. and Sears, Roebuck & Co. are among retailers who have warned Wall Street analysts over the past few days that their first-quarter earnings won't meet expectations. Their announcements come as the Commerce Department says overall retail sales in March dipped 0.2% from February, which itself was a lackluster month.

Retail sales trends are important to retail-property owners for several reasons, including the fact that rent paid by a tenant is often partially based on its gross sales. A good sales month can put extra cash in the property owner's coffers, but a poor one sinks right down to the owner's bottom line.

"We were expecting a very weak March, but it turned out to be one of the weakest months in 25 years," says Kurt Barnard, president of New Jersey-based Barnard's Retail Consulting Group and publisher of a newsletter that tracks industry trends. "It was really a very, very poor performance on the part of most retailers."