** Shares in Brazilian food retailer GPA BMFBOVESPA:PCAR3 fall after analysts at Citi downgraded their recommendation on the stock to "Sell" from "Neutral/High Risk"
** Citi acknowledges that GPA's management made strides in an operational turnaround, but still sees "significant challenges," particularly with sizable tax liabilities
** "The market appears to have already priced in GPA's deleveraging, with the stock up nearly 70% year-to-date (over 20% in the last month)," the analysts say in a note to clients
** They lower their GPA target price to 2.80 reais per share, from a previous 3.40 reais
** Shares in GPA are down 8.5% to 3.99 reais in Sao Paulo morning trading
** The food retailer is the biggest faller on benchmark stock index Bovespa BMFBOVESPA:IBOV, which slips 0.1%
** Year-to-date, GPA is still up more than 56%