Management hints that there may be value in stock in Form 10-K:
Page 4: "We decided that it was in the best long-term interest of all stakeholders, both credit and equity holders, to expeditiously address the Company's capital structure with the goal of reducing debt and the cost of capital to position the Company for the future, and on March 2, 2015 announced that we had decided not to pay approximately $62 million in principal and interest due on March 1, 2015 on our 2015 Convertible Notes and to use a 10-day grace period on principal due and a 30-day grace period on interest due to continue discussions with our debt holders."
Note that "equity holders" is stated. Typically, such statements simply say "stakeholders", which implicitly refers to creditors.
Page 27: "A plan of reorganization may result in holders of our capital stock receiving very limited or no distribution..."
Typically, management will state that there is no value in stock if that is the case, rather than this generic warning.
Such references to common stockholders are repeated throughout the form.