The new variable limits will be changed twice a year: May 1 and Nov. 1. CME Group said average prices for each contract will be calculated based on collected settlement prices and then multiplied by 7%. At the same time, the exchange will remove price limits for all grain and oilseed options, and all mini-sized grain and oilseed futures will have the identical daily price limits as their corresponding standard-sized futures.

“This is something we worked closely with our customers and grain industry participants to implement,” said Chris Grams, director of corporate communications at CME Group. “We determined that a percentage-based approach to daily price limits in C.B.O.T. grain and oilseed futures would further enhance these markets and offer customers even greater flexibility and transparency. This new methodology will allow price limits to expand under higher prices or retract when prices fall.”

The initial set of changes will remain in effect until the first trading day in November 2014. They are: Corn, 35¢ a bushel (from current limit of 40¢); soybeans, $1 a bushel (70¢); Chicago wheat, 45¢ a bushel (60c); Kansas City wheat, 50¢ a bu (60¢); soybean oil, 3¢ a lb (2½¢); soybean meal, $30 a ton ($20); oats, 25¢ a bushel (20¢); and rough rice, $1.10 a cwt (50¢).

The new limits also will be expanded if prices reach their initial limit during the prior day’s trading. The expanded limits are: Corn, 55¢ a bushel; soybeans, $1.50 a bushel; Chicago wheat, 70¢ a bushel; Kansas City wheat, 75¢ a bushel; soybean oil, 4.5¢ a lb; soybean meal, $45 a ton; oats, 40¢ a bushel; and rough rice, $1.65 a cwt, the CME Group said.