overhang

This morning there was a large 125K sell order at 2.70. Just after trade it disappeared. I now notice that it is back. It has the effect of creating a significant psychological resistance at this point. Is this a ploy that companies use to keep a stock price down? If so who would benefit? Finally, if BHP is p***** off at having to share their rail with the mindy project, is it possible that they might lauch a t/over bid for CSM at these prices?