In late July, the Dow Jones Industrial Average slid more than 700 points in a single session to log its worst single-day decline since October. Shares have since rebounded, and the majorstock market indexesall continue to flirt with new all-time highs, but it's worth noting that the big gains of the last year or two seem much harder to come by. Specifically, the Dow Jones is more or less flat from where it was at the start of May.That hints that gains could be tougher to score in the months ahea