Intrepid Potash (IPI) is up $1.49 to $25.45 and rallying along with its peer, Potash (POT), after BHP Billiton made a $39 billion takeover offer for POT. The deal, which Potash has rejected, would be the largest of the year. The news sparked a flurry of activity in Potash, Mosaic (MOS), and Intrepid Potash. While there appears to be two-way action in MOS and POT, the flow in IPI seems to be leaning on the bullish side. Sep 25 puts are the most actives, with 3054 and 100 percent traded on the bid. Meanwhile, buyers seem to be dominating the action in IPI Aug 26, Sep 27 and Sep 28 calls. Implied volatility is up 9.5 percent to 46.5.