Arch Coal, Inc. (ACI) is at an implied volatility extreme high of 64.92% that is greater than 93.42% of past values prior to 4/14/2010 (Close Price 26.21). On prior close, 4/13/2010, the implied volatility was 45.63% and at the 63.36 percentile. Closing price was 25.99.

Today's News on Arch Coal, Inc.