The New York Stock Exchange is threatening to de-list Arch Coal, one of Wyoming's largest coal companies.

Companies listed on the exchange have to meet certain criteria, including maintaining a market value above $50 million. Arch's value has been below that threshold for more than a month. 

The company has 45 days to submit an appeal, in the form of a plan for how it will return to compliance with the exchange's criteria.

In November, after reporting a $2 billion loss in the third quarter, the company said it was looking into the possibility of filing for Chapter 11 bankruptcy.