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, confirmation of JPMorgan Chase's (NYSE: JPM) improved $10-per-share bid for failing bank Bear Stearns (NYSE: BSC) earlier this week more than doubled the latter's share price within a few hours.

But beyond one-time blips like this lie stocks with fundamentally compelling reasons for recent momentum. The trick is in finding them -- and that's where Motley Fool CAPS comes in.

The story behind the story
CAPS is no crowd of lemmings. Its best-performing investors' 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 93,000 CAPS investors to filter out the noise and find companies displaying strong momentum.

We'll screen for companies with a stock-price increase of at least 30% in the past month, a market cap of greater than $100 million, and a beta of less than 3. That'll keep us clear of the wild, pump-and-dump land of penny stocks.

Here's a sample of stocks our screen returned:

Company

CAPS Rating
(Out of 5)

1-Month
Price Change

Portfolio Recovery Associates (Nasdaq: PRAA)

*****

37.9%

Boston Beer (NYSE: SAM)

*****

37.5%

Crystallex International (AMEX: KRY)

***

42.8%

Netflix (Nasdaq: NFLX)

***

33.5%

Beazer Homes (NYSE: BZH)

*

35.9%

Return data is calculated as the difference between the closing price on Feb. 22 and the closing price on March 25, as per MSN Money's screen. Star ranking from CAPS. Data as of March 25.

Let's burrow down through this list of stocks that have thumped the market in the past month and find out the story behind the numbers.

Brewing growth
In my years as an analyst and writer, I've come across literally hundreds of fervent investors who not only "buy what they know," but zealously support their investment by pitching the products to friends, family, and anyone else with a bare minimum of purchasing power. I have no doubt, then, that at least a few Boston Beer investors were buying rounds at their local pubs in celebration, after the brewer posted heady fourth-quarter earnings. The maker of Sam Adams enjoyed 25.7% sales growth, partially boosted by price increases.

As fellow Fool Rich Duprey recently observed, though, I find Boston Beer's current valuation less palatable than the product itself, now that shares have surged almost 40%. "Beer goggles" have long been a scapegoat for regrettable courtship decisions, and I'm thinking that an alcohol-induced stupor may be impairing the judgment of any investors who find Boston Beer attractive at these levels.

Maybe the strong Sam Adams brand merits Boston Beer's high earnings multiple (which stood at 32.4 after yesterday's close), but it certainly leaves a lot less margin for error in an operation still faced with rising commodity prices. While long-holding investors have been rewarded for their patience, potential new investors may want to consider whether it's prudent to dive in at today's level.

Whether or not excessive consumption of the company's products is a factor, CAPS investors still hold Boston Beer in high regard. Of the 748 investors currently rating the company, 720 are bullish on Boston Beer's prospects, believing it will outpace the broader market in the future. Maybe it's my sobriety talking, but I'm more inclined to wait for a sale on the stock to make sure I'm not paying a lousy price for a great company.

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

Add your take on these or any of the 5,500 stocks that our 93,000-plus investors 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.

With stocks like selection Portfolio Recovery Associates, the Motley Fool Hidden Gems newsletter service is beating the S&P by 24 percentage points. To see which stocks Bill Mann and Seth Jayson recommend today, take a free 30-day trial.

Fool contributor Dave Mock has his own story, but he needs a few bottles of Sam Adams Black Lager to tell it right. He owns no shares of companies mentioned here. Dave is the author of The Qualcomm Equation. Netflix is a Stock Advisor recommendation and JPMorgan is an Income Investor recommendation. The Fool's disclosure policy has the momentum of a freight train, but can stop on a dime.