Supermarket and mini-market stocks are on the rebound. As of Monday’s IBD, the group was No. 11 among 197 industry groups. Only six weeks ago, the group was No. 60. Six weeks ago, any discussion of the group would have begun with October 2013. The group hit a weekly closing high on Oct. 25 of that year. The decline from there was steady until the group began advancing six weeks ago. What happened?