"Arch Coal (NYSE: ACI) is fired up from its first quarter earnings; the results were well above analysts expectations," notes Joseph Hargett.

And with 13.5 million shares of the stock sold short, the analyst with Schaeffer's Research explains, "Shorts account for about 9.5% of the stock's float, which could result in a short squeeze." Here is his review.

"Net income nearly tripled to $81.1 million, or 56 cents per share. Revenue for the auarter rose to $699.4 million from $571.3 million. For the year, Arch Coal lifted its earnings estimate to a range of $2.40 to $2.80 per share, versus Wall Street's consensus view for $2.43 per share.

"Digging into the report, the company noted that profit margins were particularly wide in the Central Appalachia region, while higher prices for coal and cost controls also contributed to the results. Arch noted that the average sales price per ton rose 9.7% to $18.49 from $16.85, while the cash cost per ton rose less than 1% to $13.05 from $12.93.