Arch Coal (NYSE: ACI) opened at $51.50. So far today, the stock has hit a low of $46.04 and a high of $51.69. ACI is now trading at $46.54, down $7.70 (-14.20%). The stock hit its 52-Week high of $77.40 in June and set its 52-Week low of $29.36 in August. Shares of Arch Coal have been plunging today following declining coal futures....(Click the story link or go to http://www.marketintelligencecenter.com for the full story)