A big part of this is the airlines reacting to fuel prices but still...
Norfolk Southern hit its high in mid-January, Union Pacific in early Feb.
From Bespoke Investment Group:
...As shown below, the Dow Jones Industrial Average has been making new highs in recent weeks, while the Transports index has been struggling. The Transports index is having a tough time even holding onto its 50-day moving average, while the DJIA remains overbought. Time will tell how this plays out, but rest assured that we'll be hearing more and more about this negative divergence in the coming days.