Shares in AIM-listed listed anthracite coal mining company Atlantic Coal slid slightly on Tuesday, the same day that the company announced an update in relation to an option agreement to acquire additional anthracite mining assets in Pennsylvania.The option - which is exercisable at the company's discretion - has an exercise price of $35m and, following a previous extension, the company said the exercise period ended on March 31st. The company said that as a result of the size of the exercise price, the acquisition of the assets in question would be likely to constitute a reverse takeover under the AIM Rules for Companies and would therefore be subject to shareholder approval. Atlantic Coal reported that due diligence and funding discussions were ongoing but would not be completed prior to the expiry of the option exercise period. The company said it had had discussions with the vendor in connection with the extension of the option exercise period and anticipated that this would be agreed shortly. The company stated: "However, there can be no certainty that the vendor will in fact agree an option extension or that such an extension will be on acceptable terms to the company."Atlantic Coal's share price was down 8.70% to 0.21p at 10:22 on Tuesday.MF