Patriot Coal Corp. (PCX) dropped after cutting the forecast it made a week ago for sales of steelmaking coal mined in Appalachia because of a potential default by a customer.

Patriot issued its forecast outside of regular trading hours on U.S. markets. Patriot fell 3.1 percent to $4.68 at 8:38 a.m. in New York.

The company sees sales in the second quarter through the fourth quarter of 3.9 million tons at an average price of $142 a ton, St. Louis-based Patriot said in a statement after the close of regular trading yesterday. That compares with a May 8 projection of 4.9 million tons at $138 a ton.

Patriot also revised its 2013 forecast for Appalachian metallurgical coal to 200,000 tons at $122 ton from 400,000 tons at $120 previously.

Patriot also produces thermal coal, which is used to generate electricity. The company’s shares fell 43 percent this year through yesterday amid a decline in U.S. coal shipments to power stations as some utilities switch to natural gas, which fell to a 10-year low last month.

To contact the reporter on this story: Simon Casey in New York at scasey4@bloomberg.net

To contact the editor responsible for this story: Simon Casey at scasey4@bloomberg.net