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 ATP Oil & Gas (Nasdaq: ATPG). This promising driller has properties around the world, in the Gulf of Mexico, the North Sea, and off the coast of Israel, but the Gulf oil spill two years ago and the resulting deepwater drilling moratorium hamstrung its operations. Now, the company is dealing with huge debt levels. Let's take a quick look at how the stock is doing so far this year.

Stats on ATP Oil & Gas

2012 YTD Return (45.5%)
Market Cap $173 million
Revenue, Most Recent Quarter $147 million
Year-Over-Year Revenue Growth, Most Recent Quarter (12%)
Net Loss, Most Recent Quarter ($145 million)
CAPS Rating (out of 5) ***

Source: S&P Capital IQ.

ATPG Total Return Price Chart

ATPG Total Return Price data by YCharts

Why is ATP Oil & Gas falling to new depths in 2012?
ATP Oil & Gas has attracted investors for years because of the huge potential of its properties. From the estimated 1.5 trillion to 3.4 trillion cubic feet of natural gas in the to untapped resources in the North Sea and the company's longtime holdings in the Gulf of Mexico, all of ATP's fields could eventually produce massive amounts of oil and gas. Just yesterday, the company said that it had made a big natural-gas strike at one of its Israeli wells, pushing shares up 14%.

ATP can't blame overall industry conditions anymore for its woes. Competitor Ensco (NYSE: ESV) has grown immensely after its acquisition of Pride International, and both it and Transocean (NYSE: RIG) have seen greater utilization of their rigs, especially as the impact of the Gulf moratorium has disappeared. Where the money seems to be, though, is in drilling activity itself rather than in the fields that get drilled. Seadrill (NYSE: SDRL) and DryShips (Nasdaq: DRYS), through its Ocean Rig spinoff, have both taken advantage of high day rates for deepwater drillships while avoiding much of the risk of having to produce big finds.

By contrast, ATP has huge amounts of debt, to the point where now even if the company starts performing well, servicing payments to bondholders could well prevent shareholders from ever sharing in the bulk of its profits. With the company having apparently scared off its prospective new CEO, ATP will be in the fight of its life for quite a while.

ATP Oil & Gas will have to work hard to avoid having its debt crush its future. But if you like energy, we've got another stock that we think has a better chance to deliver strong gains in the future. 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 ATP Oil & Gas 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. The Motley Fool owns shares of Transocean, Seadrill, and Ensco. Motley Fool newsletter services have recommended buying shares of Seadrill. 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.