Arch Coal Inc. said Friday its second-quarter profit tripled on soaring global prices and the company boosted its outlook after beating Wall Street expectations easily.

The performance, on the heels of similar big numbers Wednesday from coal-mining counterpart Peabody Energy Corp., sent Arch's shares climbing more than 9 percent, or $4.70, to close at $55.64 Friday.

St. Louis-based Arch _ one of the nation's biggest coal producers _ reported net income of $113 million, or 78 cents per share in the latest April-through-June period. That compared with $37.6 million, or 26 cents per share, during the same period last year, in which Arch's profit dove 46 percent after it reined in production amid a softer market.

Revenue rose to $785.1 million, from $598.7 million in last year's second quarter, pushed along by higher sales prices in every one of its operating regions.

Analysts surveyed by Thomson Financial had expected earnings per share of 64 cents and revenue of $737.1 million.

Arch said it now expects profits of $2.50 to $2.85 per share, given what Arch's top executive called "our confidence in coal market fundamentals and in the company's future growth prospects." The company had upped its 2008 earnings outlook just three months ago to $2.40 to $2.80 per share, up from its previous prediction of $2 to $2.50 per share.

"We expect 2008 to be a record year for Arch," Steven Leer, Arch's chairman and chief executive, told investors during a conference call. "Our tighter and stronger guidance is indicative of our confidence in the coal market fundamentals and in our ability to capitalize on these strong market trends.

Calyon Securities' Gordon Howald on Friday reiterated his "buy" rating on Arch and the $100 price target he's set for it, arguing in a research note that "we believe Arch Coal is well-positioned to demonstrate continued (year-over-year) growth."

Arch sold 34.4 million tons of coal during the quarter, compared with 33.3 million tons during the same period last year. Each ton Arch sold fetched on average $21.04, up from $16.42 a year ago and $18.49 over this year's first three months. The company's operating margin per ton averaged $4.21, more than double the $1.75 average a year ago.

The company's operating margin increased roughly six-fold, to $20.16 from $3.51.

Arch, which extracts the bulk of its coal from its western U.S. operations, said sales of its coal mined from Wyoming's Powder River Basin were off by 1 million tons from this year's first three months because of bad weather.

Before retreating in recent weeks, coal prices had been on a tear. Seaborne coal used to produce the steam that drives turbines in northern Europe surpassed $200 per metric ton in June, when prices of Central Appalachian steam coal crossed the $100-per-ton threshold, Arch said.

Over the first half of this year, Arch said it earned $194.1 million, or $1.34 per share, on revenues of $1.48 billion, compared with $66.3 million, or 46 cents per share, on $1.17 billion in revenues during the same period last year.

Arch's latest numbers offered more evidence of the coal sector's strength. On Wednesday, St. Louis-based Peabody reported second-quarter profits that more than doubled to $233.4 million. Continued...