As we've hit the halfway point for 2012, now's a good time to look back at what's happening with the stocks that interest you. By making sure you know the important things that a company accomplished -- as well as the setbacks it experienced -- you can make a better decision about whether it's a smart investment for your portfolio.

Today, let's take a look at Arch Coal (NYSE: ACI). The coal industry has had an amazing run in recent years, as huge demand for overseas markets has helped boost production and prices. But the combination of the Chinese economy slowing down and rock-bottom natural gas prices has sent coal prices plunging, and Arch Coal has fallen with them. Let's take a quick look at how the stock is doing so far this year.

Stats on Arch Coal

2012 YTD Return (50.5%)
Market Cap $1.50 billion
Revenue, Most Recent Quarter $1.04 billion
Year-Over-Year Revenue Growth, Most Recent Quarter 19.1%
Net Income, Most Recent Quarter $1.2 million
Year-Over-Year Net Income Growth, Most Recent Quarter (97.8%)
CAPS Rating (out of 5) ****

Source: S&P Capital IQ.

Why hasn't Arch Coal caught fire this year?
Energy markets are intertwined; changes in one market have impacts on other markets. The years-long boom in natural gas production that resulted from innovative drilling techniques to take advantage of deposits in shale formations has changed the economics of energy. With natural gas prices still near decade-lows, Duke Energy (NYSE: DUK) and other electric utilities have shifted some of their electrical generation from coal to gas.

The fallout in the coal industry has been extreme, and Arch Coal can hardly count itself as the worst affected. Both Alpha Natural Resources (NYSE: ANR) and CONSOL Energy (NYSE: CNX) have closed some of their mining operations, while Patriot Coal (NYSE: PCX) has both closed its mines and is desperately trying to restructure its debt to avoid larger problems. Arch has had to cut its dividend sharply in order to conserve cash.

As Fool contributor Sean Williams has pointed out, though, coal will continue to be a major part of the energy picture in the U.S. and beyond. With costs of converting electrical facilities to natural gas adding up to nearly three-quarters of a trillion dollars, it'll take a long time for coal to disappear even if everyone wants it to go away.

Arch Coal is down and out right now, but it has good long-term prospects if it can weather the storm. But if you'd rather pick an energy stock that won't make you wait, we've got an idea that has a better chance to deliver strong gains sooner. Read about it right here in The Motley Fool's special free report on the energy industry and its best prospects.

Click here to add Arch Coal to My Watchlist, which can find all of our Foolish analysis on it and all your other stocks.

Fool contributor Dan Caplinger doesn't own shares of the companies mentioned. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Fool has a disclosure policy.