The decrease in short interest for W.W. Grainger suggests that investors are becoming more optimistic about the company's stock, which could lead to a short-term increase in its price. The fact that GWW's short interest is lower than its peer group average further supports the potential for a positive impact on the stock price. However, the article also cautions that a decline in short interest does not necessarily mean the stock will rise in the near term, which is why the importance is not rated higher.