ATH Resources, one of the UK's largest coal producers, said it faced a comprehensive review and restructuring of its business after some of its debt was bought by an investment fund.
It said in light of the development, and given the existing level of liabilities, "it is unlikely that existing shareholder value will be maintained".
The firm said its lenders, HSBC and Clydesdale Bank had sold some of its banking facilities and their related rights to Guernsey-based BECAP Fund.
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"As a result of initial discussions with representatives of BECAP Fund the board understands that a comprehensive review and restructuring of the Group's business," the statement said.
"Following completion of the review the new lender may be prepared to inject new capital into a restructured business."
Shares dived 54.5% following the announcement, leaving them 98.9% down on a year ago.
