PR-10-47 -- PSC Approves Change To AmerenUE’s Electric Fuel And Purchased Power Adjustment Charge

Contact: Kevin Kelly (573) 751-9300

FOR IMMEDIATE RELEASE -- SEPTEMBER 10, 2009

JEFFERSON CITY---The Missouri Public Service Commission has approved a request filed
by Union Electric Company d/b/a AmerenUE to adjust the fuel and purchased power adjustment
charge (FAC) on the bills of its electric customers.

In a rate case decision in January, the Public Service Commission determined AmerenUE met
the statutory standard to implement a fuel adjustment clause in order to address fuel and purchase
power cost volatility. Base electric rates were established in that rate case reflecting a certain level of
fuel and purchase power costs. The fuel adjustment clause will reflect increases or decreases in those
costs above or below those set in base rates.

AmerenUE stated in its application that the proposed adjustment to customer rates reflects
changes in its fuel and purchased power costs net of off-system sales revenues during the period of
March 1, 2009 to May 31, 2009.

The FAC adjustment will result in a decrease to a typical residential customer’s bill of
approximately $0.40 a month. The adjustment takes effect September 24, 2009.

AmerenUE serves approximately 1.2 million electric customers in Missouri.

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Case No. ER-2010-0044