BRISTOL, Va. (AP) -- Coal producer Alpha Natural Resources' fourth-quarter loss widened, stung in part by lower coal shipments, a large tax charge and a loss on early debt extinguishment.

Its adjusted loss beat analysts' estimates, but revenue missed Wall Street's view.

The company also reduced the low end of its 2014 outlook for coal shipments because of soft pricing.

Its shares fell in Wednesday premarket trading.

For the three months ended Dec. 31, Alpha Natural lost $358.8 million, or $1.62 per share. That compares with a loss of $127.6 million, or $0.58 per share, a year earlier.

The latest quarter included a $205.1 million tax charge, as well as some other charges. It also included a $7.4 million loss on early debt extinguishment, compared with a $773,000 gain a year earlier.

Income tax expense rose to $92.5 million from $26.8 million.

Removing the charges and other items, the company lost $0.52 per share.

Analysts polled by FactSet expected a loss of $0.64 per share.

Revenue fell 30% to $1.09 billion from $1.56 billion mostly due to lower average realizations and fewer shipments of metallurgical and steam coal. Wall Street was looking for $1.18 billion in revenue.

Alpha Natural sold 20.6 million tons of coal in the quarter, down from 25.9 million tons a year earlier. The weighted average coal margin per ton was $4.57, down markedly from $17.45 a year ago.

Metallurgical coal shipments declined to 4.4 million tons from 4.9 million tons. Shipments of Powder River Basin coal fell to 9.3 million tons from 11.6 million tons a year earlier. Eastern steam coal shipments dropped to 6.8 million tons from 9.4 million tons.

Alpha Natural's full-year loss narrowed to $1.11 billion, or $5.04 per share, from a loss of $2.44 billion, or $11.06 per share, the previous year.

Its adjusted loss was $2.15 per share.

Annual revenue dropped 29% to $4.95 billion from $6.97 billion.

For 2014, the company now anticipates coal shipments between 77 million and 90 million tons. Its prior forecast was for 79 million to 90 tons.

Alpha Natural said that prices are soft for low-quality metallurgical coals, which are currently selling below thermal-coal prices.

The company's stock fell $0.11, or 2.1%, to $5.15 before the market opened.