The Dow Jones Transportation Average DJT, +0.76% rallied 19 points, or 0.2%, in morning trade, to bounce sharply off earlier lows that would have put it on track to trigger a "sell" signal from the century-old Dow Theory, as explained by MarketWatch senior columnist Mark Hulbert. The Dow transports were down as much as 71.95 points, or 0.7%, at the intraday low of 10,109.47, which was below the Feb. 9 closing low of 10,136.61. A close below that level would create a pattern of lower highs and lower lows, a Dow Theory definition of a downtrend, since the Jan. 12 record close of 11,373.38. It would trigger a Dow Theory sell signal, which would mark the beginning of a new bear trend, because it would confirm a similar pattern created by the Dow Jones Industrial Average DJIA, +0.51% , which closed below its February low on Friday. The Dow industrials were recently up 84 points.