Even on the market's worst days, buyout news and other short-term forces can send individual stocks up by 10%, 25%, even 50%.        

For example, shares in small-cap biotech company Antigenics (NASDAQ:AGEN) multiplied in value several times over in the days following positive news about its cancer vaccine Oncophage, though some biotech investors remain skeptical.

But beyond less-predictable events like that one lie stocks with fundamentally compelling reasons for recent momentum. The trick is to find those stocks -- and that's where Motley Fool CAPS comes in.

The story behind the story
CAPS is no crowd of lemmings. Its best-performing members' opinions do more to shape each company's rating than the picks of their poorer-performing peers. Let's use the collective wisdom of more than 135,000 CAPS members to filter out the noise and find companies offering strong momentum.

We'll use CAPS' handy stock screening tool to quickly zero in on companies with a stock price increase of at least 25% in the past four weeks, a market cap of greater than $100 million, and a beta of less than 3. Below is a sample of stocks that our screen returned. If you'd like, run this screen yourself -- just keep in mind that results may change as the market does.

Company

CAPS Rating
(Out of 5)

4-Week
Price Change

Alvarion (NASDAQ:ALVR)

*****

59.2%

Rubicon Minerals

*****

27.8%

BioDelivery Sciences (NASDAQ:BDSI)

*****

26.4%

Satyam (NYSE:SAY)

****

51.9%

Cray

***

82.8%

Source: Motley Fool CAPS. Price return from May 29 through June 26, 2009.

High-wireless act
Alvarion is joining with wireless giants like Clearwire and Sprint Nextel (NYSE:S) to make WiMAX a key next-generation mobile technology standard. But the alliance faces a tough battle against the Long Term Evolution (LTE) standard, which is favored by anchor providers such as AT&T (NYSE:T) and Verizon (NYSE:VZ). However the head-to-head battle unfolds in prime markets, some anticipate that WiMAX will be the platform of choice to serve rural areas and emerging markets, where fixed-line networks are poorly developed. In fact, Alvarion is already benefiting with deals in places like Papua New Guinea and Nigeria.   

After a long lull, shares in the Israeli company have soared following two large contracts in more developed countries. Alvarion landed a five-year contract worth more than $100 million with U.S.-based Open Range Communications to enhance broadband access in rural areas in 17 states. It also landed a deal with Italian telecom operator Aria to deploy its WiMAX technology throughout that country. With poor global economic conditions actually increasing governments' focus on expanding wireless broadband, many CAPS members see the possibility of more lucrative deals to come. In CAPS, 97% of the 860 members rating Alvarion expect it to outperform the S&P 500.

Bring the pain
Shares in BioDelivery Sciences have more than doubled so far this year, with investors growing increasingly confident about the eventual approval of its pain therapy Onsolis, for which the company expects to receive FDA approval soon. The company recently received an update from the FDA regarding its new drug application for Onsolis; although the agency is late with its response, it's close to a decision and will not file a review extension.

BioDelivery recently raised more cash from exercised warrants, a stockpile it expects will help carry the company into the fourth quarter without any more financing. This new money adds to the millions raised from its partner, Swedish drugmaker Meda, earlier this year to support its testing and trials. With the possibility that the company will receive more milestone payments upon approval and launch of the drug, many investors remain bullish on BioDelivery Sciences' prospects; 70 of the 73 CAPS members rating BioDelivery Sciences see the stock beating the S&P 500. 

And you?
What's your story? Whether you buy the tale of a stock that's soaring or souring, your own research is more important than collective opinions. But the CAPS community's group intelligence can make your due diligence a whole lot easier.

Add your take on these or any of the nearly 5,300 stocks that our 135,000-plus members have covered in Motley Fool CAPS. It's totally free to be a part of the community, and the payback is more than worth it.

Looking to nab tomorrow's big winners early, the Motley Fool Rule Breakers service has already recommended Alvarion to subscribers. To see what other rule-breaking stocks David Gardner is picking today, take a free 30-day trial.

Fool contributor Dave Mock has his own story, but there's no "happily ever after" at the end of it. He owns no shares of companies mentioned here. Alvarion is a Rule Breakers pick. Sprint Nextel is a Inside Value recommendation. The Fool's disclosure policy has the momentum of a freight train, but can stop on a dime.