For those looking to find strong Retail-Wholesale stocks, it is prudent to search for companies in the group that are outperforming their peers. Has Groupon (GRPN) been one of those stocks this year? 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.Groupon is one of 213 individual stocks in the Retail-Wholesale sector. Collectively, these companies sit at #15 in the Zacks Sector Rank. The Zacks Sector Rank c ...