Sometimes an industry group’s ranking says little about what’s truly happening internally. Retail/Wholesale-Building Products was No. 64 out of 197 groups in Wednesday’s IBD, up from No. 111 six weeks ago. Normally, this status wouldn’t be worthy of much attention. But this group is a bipolar story; it houses both strong outperformers and miserable laggards. Since a closing low on Oct. 15, the S&P 500 has gained as much as 12.4%, vs.