The last pair is of iShares Dow Jones Transportation Average Index Fund ( IYT) over SPDR Dow Jones Industrial Average ( DIA) . This indicator has been used by analysts for a long time to determine the strength of rallies. The story goes that if the transport index outperforms industrials, then companies are shipping out product, which should show up in the earnings. Although factory output has been unimpressive, this pair looks to have found a near term bottom. A rise in the indicator should give further strength to the equity rally we are immersed in. At the time of publication the author held no positions in any of the stocks mentioned. Follow @AndrewSachais This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.