This stock gets a momentum grade and performance grade of A+; there are not many stocks that get an A+ performance or momentum grade right now. This is a rare bird. That being said, remember that this is a smaller stock. Smaller stocks carry greater risk. For this reason, I'm a big proponent of owning 25 to 35 stocks in your portfolio that fit your risk profile. Valuation Next let's take a look at the valuation of Opko. This is difficult to do right now because the company is still losing money. In fact, Opko is expected to lose 17 cents per share this year. However, when I look at the company's sales growth over the last four quarters, I see growth in sales up between 73% and 133% from quarter to quarter. It would be pretty hard to carry on a trajectory like that of sales growth and not eventually crossover the line into profitability. I think that with Opko's products and pipeline it has ample upside potential going forward. Stock Chart: Lastly, we have to take a look at the stock chart. Opko's chart was dead in the water from March until August but then it started taking off. And it's been taking off ever since. I bought Opko and I think you can see why as it has the numbers to back it up; it fits my style of investing. Now it is a member of my aggressive growth portfolio. Out of 3,575 stocks, Opko comes in as the number-one-ranked stock in my Best Stocks Now! app. Are there guarantees in the market? No. But can you do your best to try to put probability on your side? Yes. At the time of publication the author had no position in any of the stocks mentioned.Follow @billgundersonThis article was written by an independent contributor, separate from TheStreet's regular news coverage.