"A former Arch Coal employee is suing the trustees of the company's retirement plan, alleging they invested retirement savings in Arch stock though they should have known it was a risky investment.... The suit comes as Arch, like other coal companies, is dealing with the effects of a depressed coal market; it reported a first-quarter loss of $113.2 million on revenue of $677 million and was recently warned by the New York Stock Exchange that it is out of compliance with the market's rule requiring an average price of $1 per share of common stock for 30 consecutive trading days."