Among other things, the Dow Theory says that the movements on one of the averages (industrial) must be confirmed by the movements on the other average (transportation). In January/04, the transportation average started to diverge negatively in comparison to the industrial average.
Later that was confirmed as an alert signal and both the averages fell to their support: the transportation average touched the 200 MA and the industrial average stopped falling at its 38% Fibonacci retracement considering the bullish move from August/03 to February/04.
If these support levels are maintained, rallies can happen on the next few weeks.