The underperformance of the Dow Transportation Average this year may be the reason why the overall market remains range-bound and why it may pull back, some market watchers believe.
As CNBC Pro highlighted earlier this year, Transports have been sending a warning signal for stocks, which have been trapped below the same level since February.
So far in 2015, the Dow Transportation Average is down 6 percent compared with an increase of 2 percent for the Dow Industrials, a rise of 3 percent for the and a gain of 6 percent for the Nasdaq Composite.
That divergence, to some investors, may be canary in a coal mine for a potential significant decline ahead.
"Something isn't right with the Dow Jones Transportation Average," says Carter Worth, head of technical analysis at Cornerstone Macro.