Investors interested in Retail-Wholesale stocks should always be looking to find the best-performing companies in the group. Costco Wholesale (COST) is a stock that can certainly grab the attention of many investors, but do its recent returns compare favorably to the sector as a whole? One simple way to answer this question is to take a look at the year-to-date performance of COST and the rest of the Retail-Wholesale group's stocks.Costco Wholesale is one of 218 individual stocks in the Retail-Wholesale sector. Collectively, these companies sit at #10 in the Zacks Sector Rank. The Zacks Sector Rank includes 16 different groups and is listed in order from best to worst in terms of the average Zacks Rank of the individual companies within each of these sectors.The Zacks Rank is a proven model that highlights a variety of stocks with the right characteristics to outperform the market over the next one to three months. The system emphasizes earnings estimate revisions and favors companies with improving earnings outlooks. COST is currently sporting a Zacks Rank of #2 (Buy).Within the past quarter, the Zacks Consensus Estimate for COST's full-year earnings has moved 2.20% higher. This signals that analyst sentiment is improving and the stock's earnings outlook is more positive.Our latest available data shows that COST has returned about 16.04% since the start of the calendar year. Meanwhile, stocks in the Retail-Wholesale group have gained about 12.58% on average. As we can see, Costco Wholesale is performing better than its sector in the calendar year.Looking more specifically, COST belongs to the Retail - Discount Stores industry, which includes 10 individual stocks and currently sits at #60 in the Zacks Industry Rank. Stocks in this group have gained about 14.14% so far this year, so COST is performing better this group in terms of year-to-date returns.COST will likely be looking to continue its solid performance, so investors interested in Retail-Wholesale stocks should continue to pay close attention to the company.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Costco Wholesale Corporation (COST): Free Stock Analysis Report To read this article on Zacks.com click here.