Notice of Market Implementation Error

Notice of Market Implementation Error

Notice is hereby provided to Market Participants that during the April 9, 2008 operational testing of the Ancillary Services Markets software a price administration error occurred resulting in the inclusion of one test interval in the calculation of final Ex Post Prices for hour ending 1500. The Marginal Energy Cost (“MEC”) for hour ending 1500 as posted on April 10th was $31.12. Had the test interval been excluded the MEC would have been $31.41 resulting in a less than one percent inaccuracy. The Midwest ISO did not become aware of this issue until April 14, 2008. As a result, the Midwest ISO is limited by section 43.8(b) of the Energy Markets Tariff from making a price correction for hour ending 1500. The Midwest ISO has taken steps to assure that such test intervals will not be included in future final hourly Ex Post Prices.