Editor's note: A previous version of this article listed Gastar Exploration in the table below. Gastar Exploration recently completed a reverse stock split, which affected the stock's price. The Fool regrets this error.

Some stocks are one-hit wonders, making a big splash when they first appear, then quickly fizzling into obscurity or oblivion. But for other stocks, that initial big move is only a preview for even bigger and better gains to come.

Today, we've compiled nine stocks that made some of the biggest upward moves over the past month. We'll then pair that list with the ratings issued by our Motley Fool CAPS community. The higher each stock's rating, the greater CAPS members' faith in that company's ability to keep on beating the market.

Stock

30-Day % Change

CAPS Rating

Rentech (NYSE:RTK)

421.74%

**

American Axle & Manufacturing (NYSE:AXL)

319.12%

*

Select Comfort

215.79%

***

Radian Group

214.80%

**

ArvinMeritor (NYSE:ARM)

129.21%

**

Crocs

105.48%

*

Boise (NASDAQ:BZ)

96.76%

****

Century Aluminum (NASDAQ:CENX)

88.56%

****

UAL (NASDAQ:UAUA)

70.21%

*

30-day % change from July 17 to Aug. 18.

As the markets whipsaw to changes in consumer sentiment, there will be weeks like this one, in which we see gains that are exceptionally ahead of the pace of prior weeks' movers and shakers. So before we get shaken out again, let's see why the CAPS community thinks some of these companies might outperform the market.

A mighty temblor
Your first profitable quarter ever is bound to make the market enthusiastic, and such was the case for Rentech, which benefited from lower natural gas prices and larger sales of synthetic jet fuels as it posted record profits in the second quarter. It followed that up with a deal to supply airlines with synthetic jet fuel made from waste such as yard clippings. Rentech says the deal is the first of its kind to supply several airlines with the renewable diesel fuel.

Rentech is brimming with confidence now. It raised guidance for the year, assured that natural gas prices will remain below the levels it budgeted for and on being able to sell more jet fuel. CAPS member hatchjcp thinks the company is big news:

Huge growth story. Fertilizer stock that is just starting to make alternative fuel such as jet fuel. They supply the air force and just got a contract for eight airlines at the LA airport on Aug. 18, 2009.

Strong as steel
News that Aluminum Corp of China, China's largest alumina producer, was raising prices didn't hurt the cause of Century Aluminum. The latter company has been striving to bolster its financial position by selling assets, but its stock had already made a big move upward before Chinalco's big announcement. Despite reporting its third consecutive quarterly loss, a stronger-than-expected surge in June's housing numbers, combined with the company's own position that aluminum demand was ticking northwards, were enough to send Century Aluminum's shares higher.

CAPS members remain bullish on Century; 93% of those rating it think it will outperform the market. Though DaveZzzz3 thinks it remains at depressed levels, it has still outperformed the other 190 or so stocks in the CAPS Metals & Mining sector, which rose just 6% on average over the past 30 days.

Still feeling the aftershocks
American Axle & Manufacturing was a one-day marvel the other day, more than doubling in value after General Motors agreed to infuse it with $210 million to help it restructure. Of that sum, $110 million is related to costs associated with GM's own bankruptcy, while the other $100 million is a term loan facility. Highly rated CAPS All-Star member TSIF finds it difficult to generate any enthusiasm for American Axle's situation:

This rally the past few months has, unfortunately, way too much basis in companies with minimal outlook, just because they were beaten to a pulp. American Axle if/when, they get their credit in shape stands to gain from a $110 Million "gift" from GM for behaving during their bankruptcy, but debt is over $1B and rising. Even if AXL is successful in debt restructuring, covenants, and avoiding Bankruptcy, they still have YEARS to go to be profitable. Book value per share is NEGATIVE $13.00, net tangible assests are negative by over $800 Million, and quarterly revenue off by over 50% yoy. Where does an extension on a credit overhaul warrant a share price double???

Shake, rattle, and roll
With these stocks shaking the market this past month, it pays to start your own research on them at Motley Fool CAPS. Read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made -- all from a stock's CAPS page.

Try any of our Foolish newsletter services today, free for 30 days.

Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings here. You can shake, rattle, and roll The Motley Fool's disclosure policy, but it still won't break.