American Eagle Energy became the fourth U.S. energy producer to file for bankruptcy protection in the aftermath of the big drop in crude oil prices. The Colorado-based company that buys and develops oil wells in the Bakken oil fields of North Dakota and Montana filed for chapter 11 bankruptcy protection on Monday in Denver’s bankruptcy court. American Eagle Energy, which recently missed an interest payment on its debt, listed assets of $222 million and liabilities of $215 million. Shares of American Eagle Energy traded for as much as $7.05 less than a year ago, reflecting the stunningly fast collapse of...