The Retail-Wholesale group has plenty of great stocks, but investors should always be looking for companies that are outperforming their peers. Is Costco (COST) one of those stocks right now? A quick glance at the company's year-to-date performance in comparison to the rest of the Retail-Wholesale sector should help us answer this question.Costco is a member of the Retail-Wholesale sector. This group includes 210 individual stocks and currently holds a Zacks Sector Rank of #10. The Zacks Sector Rank conside ...