NEW YORK (TheStreet) -- Shares of Dollar General (DG - Get Report) are down slightly on Friday for the second straight session, after the company beat on EPS estimates but missed on revenue expectations in its quarterly report Thursday. 

Four firms have now come out to defend Dollar General, saying that the company's return on investment is very good, TheStreet's Jim Cramer, co-manager of the Action Alerts PLUS portfolio, said on CNBC's "Stop Trading" segment. 

This is a tough sector, for it seems when a retailer disappoints investors, it becomes hated, after which it's hard to get back in investors' good graces, Cramer said, adding that Macy's (M - Get Report) and Williams-Sonoma (WSM - Get Report) have also struggled. 

DG Chart
Dollar General DG data by YCharts

It will be interesting to learn if Dollar Tree (DLTR - Get Report) is taking market share from Dollar General when the former reports earnings next week, he said. 

If it hasn't been taking share and instead there's an overall weakness in the group, then investors need to be careful since the dollar store industry has been so strong, Cramer concluded. 

At the time of publication, Cramer's Action Alerts PLUS had no position in companies mentioned.