European retailers have been unlikely stock market stars this year, but a long spell of high borrowing costs and inflation has started to bite, so wary investors will be looking for reassurances from the likes of H&M and Zara-owner Inditex when they issue business updates this week. Last year, investors and strategists expected retailers' margins to take a hit, as inflation eroded households' discretionary spending and some of the region's heavyweights warned of tough months ahead. The broader STOXX 600 is up by 7% this year, meaning retailers are outperforming by the most on record.