If you've ever sought to get seriously rich from stocks, then you've owned a tweener.

Neither up-and-coming superstars nor dominant veterans, tweeners are poised precariously in between. They're not as hot as they once were, and they're vulnerable both to young upstarts and old stalwarts. But they've honed their skills enough that they're still a force to be reckoned with.

The stock market has plenty of tweeners. They'll either create billion-dollar fortunes as they come to dominate industries, as Cisco and Microsoft (Nasdaq: MSFT) have, or they'll be destroyed in the process, as Gateway almost was. That's the problem -- investing in tweeners can be dangerous and exceptionally profitable. By picking his winners well, David Gardner produced nine years of 20% average returns hunting for misunderstood multibaggers in the making. His team at Motley Fool Rule Breakers continues the tradition today.

Let's have the list
You, too, can join in the effort, thanks to Motley Fool CAPS. Each week, we'll use the database to find three-star stocks -- CAPS' own tweeners, halfway between one-star duds and five-star MVPs -- that are expected to boost earnings by at least 15% annually over the next five years. Here are the latest contenders.

Company

Recent price

5-Year Growth Estimate

Yingli Green Energy (NYSE: YGE)

$21.08

48.0%

ScanSource (Nasdaq: SCSC)

$32.97

17.3%

China Techfaith Wireless (Nasdaq: CNTF)

$4.21

22.5%

Yahoo! (Nasdaq: YHOO)

$28.38

22.5%

Chipotle Mexican Grill (NYSE: CMG)

$123.05

26.8%

Sources: Motley Fool CAPS, Yahoo! Finance.

Bear in mind that this isn't a list of recommendations -- merely candidates for further research.

Yahoo! might have been a tempting choice before Microsoft's $44.6 billion buyout offer. And Chipotle still looks tasty at $123 a share, for all of the same reasons I've cited before.

From Big Red to Big Green
But my favorite for today is Yingli Green Energy, a Chinese producer of photovoltaic cells for generating solar power. Business has been good lately. Here's how CAPS investor TexasLonghorns put it in a December pitch:

Chasing almost [its] 52 week high here but the Chinese have no choice but to find alternative energy sources or they will choke to death on their own growth. Yahoo [Finance] has this one pegged at $192.00 a share. Maybe, maybe not. But worth a shot at these prices. Volatile as all Chinese stocks seem to be these days but long term should pay off well.

Especially if management continues to be conservative. Yingli has already stockpiled 70% of the silicon it needs for 2008, and earlier today, it revealed that it is reducing the thickness of its solar-gathering wafers by 10%. The result? Less raw material, which means lower costs and -- helloooo -- higher margins. I can see a short path from there to better cash flow and, thereby, higher returns.

But that's my take. What's yours? Would you buy Yingli at today's prices? Let us know by signing up for CAPS now. It's 100% free to participate.

See you back here next week for five more top tweeners.

How great is growth? Nine stocks in the market-beating Rule Breakers portfolio, which includes Chipotle, have at least doubled. Discover all of their identities with a 30-day guest pass to the service. There's no obligation to subscribe.

Chipotle's B shares are recommended by our market-beating Motley Fool Hidden Gems service. Microsoft is an Inside Value pick. Yahoo! is a former choice of Stock Advisor.

Tim Beyers, who is ranked 13,362 out of more than 83,000 participants in CAPS, is a regular contributor to Fool.com and Rule Breakers. Tim didn't own shares in any of the companies mentioned in this article at the time of publication. Click here for Tim's portfolio and here for his latest blog commentary. The Motley Fool's disclosure policy prefers a little less conversation and a little more action.