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 listed three stocks that made some of the biggest upward moves over the past month, which we'll pair 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

1 Month % Change

CAPS Rating (out of 5)

American Apparel (NYSE: APP)

84%

**

EXACT Sciences (Nasdaq: EXAS)

51.3%

*

Xyratex (Nasdaq: XRTX)

44.5%

***

One month % change from Aug. 20 to Sept. 21.

As the markets whipsaw to changes in changes to second half economic performance, the S&P 500 has been volatile. So before we get shaken out again, let's see why the CAPS community thinks some of these companies might continue to outperform the market.

A mighty temblor
Earlier this month I said troubled retailer American Apparel was exhibiting a typical "dead cat bounce." Its finances are in turmoil, it rehired the auditor it previously fired after Deloitte & Touche resigned after taking a look at its books, and it stands a good chance of getting delisted. Sure, the stock exchange has accepted American Apparel's plan to avoid that happenstance, and it's got until Nov. 15 to file its second quarter financial statements, but that doesn't mean it won't still collapse into the maelstrom.

What helps it hold on is the following it has in fashion circles. Like more financially sound retailers like Aeropostale or even Gap, American Apparel has adherents who like its quirky style and edgy fashion sense.

While CAPS member rlich8 says the combination of a heavy debt load and a CEO that's viewed as something of a loose cannon, 85% of the CAPS community rating the retailer thinks it will outperform the averages.

A slick opportunity
With preclinical data to be presented at an upcoming American Association of Cancer Research meeting in late October, the markets appreciated Exact Sciences filing for a $150 million shelf registration for equity, debt, or other securities. The biotech says it doesn't have plans to issue anything right now, but with a two-year window open to it, the filing gives Exact Sciences the chance to move quickly if conditions are right.

It recently acquired the rights to two markers obtained from a patient's stool to test for colorectal cancer, and coupled with its own developments could be on track toward developing a commercially successful genetic screening test for colon cancer. Such markers received a black eye from Sequenom's (Nasdaq: SQNM) fiasco last year, but that biotech is moving to develop its own diagnostic tests so the sector still holds a lot of promise.

A speedy opportunity
As the recent bidding war for 3Par showed, the storage market is hot. Companies like Hewlett-Packard are using their heft to stay ahead of the competition while EMC (NYSE: EMC), which offers cloud-friendly storage solutions, could very well dominate in the future. All of which makes Xyratex an interesting company to watch.

With its IBM (NYSE: IBM) pedigree and relationships with Dell (Nasdaq: DELL) and NetApp, storage specialist Xyratex forms a unique opportunity to capture the growth the segment possesses. CAPS member umps15 pointed out a month ago that it was ready to shake things up.

The current valuation of this company is extremely low. Checking Glassdoor.com, there's some unfavorable review about management but at P/E around 5 and P/S so low at 0.26, it's hard to pass this company up. Sales this quarter alone surpassed their market value. They provide enterprise class storage (25% market share) and HDD testing methods. They are getting $750,000 of revenue per employee, which is great for a company providing engineering solutions.

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.

The Fool owns shares of Aeropostale. Try any of our Foolish newsletter services free for 30 days.

True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Motley Fool has a disclosure policy.

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.