CF Industries shares are up $1.75 to $90.30 on general strength in the Ag names following an upgrade of Potash. CF option volume is 2x daily average with notable trades being in the Jan. $65 and $75 puts; which have traded 6,050 and 3,072 contracts, respectively. Looks like seller in the $65s and buying in the $75 to establish the 1×2 ratio for a 25c net debit. The Jan. $100 call saw a 8,300 contract block purchase. CF continues to be in the midst of a three way takeover battle in which Agrium (AGU) is bidding for CF and CF is bidding for Terra (TRA).