There will always be companies that are obviously great investments -- in hindsight. Through the rearview mirror we know we should have bought Microsoft or Wal-Mart at their IPO and realized tens of thousands of percent returns over the years. Yet for every stock out there screaming "buy me," there are others that simply give us a nudge in the ribs and a knowing nod. They may be tomorrow's obviously great investments, but how do we tell them from the thousands of pretenders?

The stars walk of fame
Over on the investor intelligence site Motley Fool CAPS, we know these opportunities as four-star stocks, companies that rank higher than most of the other 5,000 stocks in the CAPS universe but are just shy of achieving stardom. In the long shadows of stocks that garner the coveted five-star rating are top-tier companies approaching greatness.

While the full "secret sauce" of how the ratings are calculated is proprietary, there are three factors that influence a stock's star rating:

  1. Whether a stock is rated "outperform" or "underperform"
  2. The length of time it is expected to perform (a few months or a few years)
  3. The ratings of the investors who make the picks.

Every player is rated just as every stock is rated. The best and brightest of these players are considered All-Stars, and since they are correct more consistently than their peers, their opinions weigh more heavily in favor of (or against!) a stock.

Searching out of the spotlight
All the attention might be focused on the five-star stocks, while decent investments slip under the radar with only four stars. Let's sift through the CAPS database and find some of these four-star companies approaching greatness:

  • NYSE Euronext (NYSE:NYX)
  • SanDisk (NASDAQ:SNDK)
  • Marvell Technologies (NASDAQ:MRVL)
  • Oracle (NASDAQ:ORCL)
  • Newmont Mining (NYSE:NEM)

Are you surprised that Oracle is on the list? And hasn't SanDisk been providing memory chips forever? It's true, they're familiar names, but sometimes we forget about the investment opportunities familiar names still represent. Just as meaningful, the 65,000 investors on CAPS are giving these companies the nod as less obvious possibilities for tomorrow's great buys. So let's delve into why these companies might merit your attention.

More than 1,800 investors have had their say on Motley Fool Rule Breakers recommendation NYSE Euronext, the operator of the New York Stock Exchange, and one out of every five is an All-Star, meaning their player rating exceeds at least 80% of the other players. As the exchange prepares to release its financials this month, it's also no secret that it continues to seek new acquisition targets. In August of this year Nasdaq (NASDAQ:NDAQ) boasted of increased trades of NYSE-listed stocks and is pursuing acquisitions of its own. To stay on top, the NYSE will need to increase its reach.

Playing on this, CAPS investor PsychoDr thinks the NYSE will benefit from the nature of its business, which pays it every time an investor enters or exits a stock.

Stock exchanges make money on transactions, right? Opt in requirements for 401(k) plans, the ever-increasing interest in the stock market as a way to make money (see subprime lending woes again), and the entire industry is consolidating. At the beginning of the year it was the talk of the town; summer hit the stock hard and made it a bargain at this price. Remember, the exchange makes money on buying and selling stocks -- not just the ups but the downs as well. I may be a bit early on the current price, but long term (my mantra): This is a plus stock.

With the stock trading more than one-third below its highs, it's priced similarly to other exchanges based on 2008 earnings. By closing trading floors, cutting costs, and if its fundamentals remain intact, the upcoming quarterly earnings ought to underscore the opportunity to buy at what amounts to a discount.

A great opportunity for you
That's the current word on NYSE Euronext, but what are your thoughts? Are these four-star stocks still investment grade material? On Motley Fool CAPS, you can give your input, which can ultimately influence how they're rated. Outperform or underperform, near-term or well into the future, your opinion counts.

Sign up today for Motley Fool CAPS; it is completely free. Let us hear what you have to say about the great and almost great companies that interest you.

NYSE Euronext is a recommendation of Motley Fool Rule Breakers. A 30-day, risk-free trial subscription shows why the market-beating stock selection service thinks the company is a five-star investment anyway. Microsoft, Wal-Mart, and Nasdaq are recommendations of Motley Fool Inside Value.

Fool contributor Rich Duprey owns shares of Wal-Mart but does not have a financial position in any of the stocks mentioned in this article. You can see his holdings here.

The Motley Fool has an approachable disclosure policy.