CHICAGO, Aug 25 (Reuters) - The CME Group will leave the maximum storage rate for deliverable Chicago Board of Trade wheat unchanged next month at roughly 8 cents a bushel per month, the exchange said in a statement on Monday.
The storage rate can fluctuate depending on changes in the spread, or price difference, between the front two CBOT wheat futures contracts. The storage rate rose in July for the first time in three years.
The spread between the CBOT September and December wheat futures contracts averaged 66.46 percent of full carry during a monthlong observation period that ended on Friday.
Under its "variable storage rates" system, the exchange raises rates when the spread averages 80 percent or more of full carry - the estimated cost to store wheat from one contract delivery to the next.
CME lowers the storage rate when the spread averages 50 percent of full carry or less, and leaves rates unchanged when the average is between 50 percent and 80 percent.
The variable rate system was introduced in 2010 as a way to keep cash and futures prices properly converging during futures delivery periods. CME September wheat futures first delivery notices are due on Aug. 29.
(Reporting by Julie Ingwersen; Editing by Jonathan Oatis)