Sector rotation is pretty much a done deal, if the Big Cap 20 is any guide. Last spring and summer, the medical sector was providing a third to a half of the names in the Big Cap 20. The summer leaders’ charts now look sad. Biogen (BIIB) is 40% off its high. Illumina (ILMN) is 33% off its high. Regeneron Pharmaceuticals (REGN) is 23% off its high. In Tuesday’s Big Cap 20, only one medical stock made the list.