Most marijuana stocks have performed poorly so far in 2018. And a few have fared pretty well. Auxly Cannabis Group (NASDAQOTH: CBWTF), previously known as Cannabis Wheaton, is in the former category, with its share price sinking more than 35% year to date. Organigram Holdings (NASDAQOTH: OGRMF) is in the latter group, with its stock jumping nearly 25% as of early July.But what goes up can go down -- and vice versa.