Shares of fertilizer company Potash (NYSE:

) have given back gains from earlier in the session and are now trading in negative territory. The stock was trading up more than 1.50%, but has been falling for the last couple of hours and is currently down 0.20% to $58.21. There have been rumors circulating today the the CME Group is considering raising margins on corn, and this may be having an effect on the fertilizer complex on Tuesday. Potash Corporation of Saskatchewan Inc. (

) is an integrated fertilizer and related industrial and feed products company. The Company owns and operates five potash mines in Saskatchewan and one in New Brunswick.