"Department stores buy goods well in advance and will maintain a broad and deep selection, benefitting from scale advantages of purchasing in large volumes," he said. By contrast, "off-price retailers buy opportunistically, late in the season, often in odd lot quantities and can get goods from vendors to store in a few days." It's no wonder Macy's wants a piece of the off-price action: T.J. Maxx and Marshalls, for example, generate about $304 in sales per square foot, a key measure of a retailer's productivity, while Macy's lags far behind, averaging an estimated $158 per square foot, according to eMarketer. It's unclear how Macy's will carve a distinct, unique niche and wow shoppers in the off-price space.