THe coal market is pretty tough going at the moment. Prices and profits are substantially down, and this sentiment is likely to be impacting HDX (in addition to capital raising selling pressure).
However one thing to be aware of is that most arrangements between coal producers and rail and port and storage providers are subject to repressive 'take or pay' contracts. that is, producers pay for space even if they don;t use it.
As a result production volumes need to be maintained in order to avoid some pretty major penalties for not taking up their rail/storage/port commitments. Miners are often better off exporting coal at a loss to ensure that they have the cash flow available to meet the requirements of service providers.
This works hopefully in HDX's favour as it means that coal production volumes are maintained during low price points of the cycle.