Monthly retail sales are going to get a lot harder to track.The largest retailer in the world announced that it will not longer supply its monthly sales results. "The company stressed that the move is a way to focus on the long-term view, but it also allows the company to escape the volatility that sometimes comes along with reporting monthly sales," says this article.Wal-Mart is joining Best Buy and Home Depot, two other large retailers that don't report monthly sales.Without knowing how Wal-Mart is performing on a monthly basis, our understanding of how the overall industry is performing will decrease tremendously. Many landlords already feel in the dark about how their tenants are performing, and their situation just got a lot darker.Stay tuned. We'll blog more in depth about this issue in BNET's retail site.