(Reuters) - U.S. railroad operator CSX reported third-quarter profit below Wall Street estimates on Wednesday, as lower coal volumes offset benefits from stronger pricing, sending its shares down 3.4% in after the bell trade.

Domestic coal demand has been hampered by a consumer shift to cheaper natural gas stockpiles for energy, while adverse weather conditions and work stoppages at Canadian railroads posed various operational challenges.

The company also said coal demand will continue to remain stressed in the short term due to sluggish performance in the U.S. steel and industrial sectors.

CSX's operating margin, a keenly watched metric, was 37.4% for the quarter, representing a 180 basis-point improvement from a year ago.

The Jacksonville, Florida-based company reported a profit of 46 cents per share for the quarter through September. Analysts' were expecting a profit of 48 cents per share, according to data compiled by LSEG.

It reported revenue of $3.62 billion in the third quarter, up 1% from a year ago, compared with analysts' average estimate of $3.67 billion.