In a sign that the world's largest retailer expects to see slowing sales this fall, Wal-Mart lowered its September same-store sales forecasts. In addition to the August 1.8% same-store sale growth given just yesterday, what lies ahead?

Wal-Mart, considered to be a huge barometer of consumer spending, can cause entire market swings when it even sighs, and lowering a current-month sale-store sales forecast can send ripples throughout the national averages. We've all seen it before if we were paying attention; I know I was.

Is the American economy -- and more even, economic growth -- predicted by Wal-Mart's numbers on a monthly and even weekly basis? Many would argue yes, and there are equal opinions on the other side of this answer as well.

It's true that Wal-Mart, by virtue of its size, is a very decent indicator of the growth (or stagnation) of the American economy -- nothing new here. But, as Wal-Mart continues to grow, it may even become a larger indicator of economic spending patterns or slowdowns that could be used to actually guide some of the marketplace, which is based on speculation more than fundamentals if you ask me.