If there were an S&P 500 version of the Olympics, which stocks would make it to the awards ceremony? Many of us might pick Apple (Nasdaq: AAPL) to take the top prize despite its disappointing last quarter. Shares of the i-everything powerhouse increased nearly 320% over the past five years. Believe it or not, though, Apple wouldn't even earn a spot on the podium.

There are three stocks that outperformed every other stock in the S&P 500 index -- including Apple. What are those stocks, and how did they do it? Start humming the Olympic theme song, and let's find out.

Bronze medal
The winner of the bronze medal in our S&P Olympics is Perrigo (Nasdaq: PRGO). Perrigo shares soared 466% during the past five years.

PRGO Chart

PRGO data by YCharts

Perrigo is the largest store brand manufacturer of over-the-counter (OTC) pharmaceuticals and infant formulas. Perrigo also makes generic prescription pharmaceuticals, nutritional products, and active pharmaceutical ingredients.

Silver medal
Alexion Pharmaceuticals
(Nasdaq: ALXN) takes the silver medal. The stock increased 586% during the last five years, adjusted for stock splits.

Alexion focuses on making products for patients who have severe and ultra-rare medical conditions. Nearly all of the company's revenue stems from sales of one drug, Soliris.

Gold medal
The winner of the gold medal for stock price performance is priceline.com (Nasdaq: PCLN). The company's shares skyrocketed by a whopping 841% over the past five years.

PCLN Chart

PCLN data by YCharts

Priceline is a leading online travel company that offers services for customers to make hotel, airline, rental car, and cruise reservations. Nearly 90% of Priceline's net income comes from international bookings.

Secret of their success
How did these three stocks outperform everyone else in share price growth? You might think that it was because they were able to show stronger earnings growth. And, yes, each of the top three companies grew earnings at impressive rates. Apple, though, had better earnings growth over the five-year period than Perrigo and Priceline did.

Apple also outperformed on other important fundamental metrics. For instance, looking at book value, all three companies showed rapid growth, but Apple beat Perrigo and Priceline with faster growth rates in book value. Similarly, all three companies showed terrific free cash flow growth over the five years, but again, Apple did better in this category than Perrigo and Priceline.

With better earnings, book value, and free cash flow growth numbers, why isn't Apple on the winners' platform next to Alexion? One possible secret to their success is better growth in return on invested capital.

ROIC represents the rate of return that a company makes on capital invested by shareholders and debt holders. With our S&P Olympians, ROIC levels themselves were not as important as the ROIC growth.

AAPL Return on Invested Capital Chart

AAPL Return on Invested Capital data by YCharts

In terms of actual ROIC, Apple is neck-and-neck with Priceline but beats Alexion and Perrigo. However, the chart below shows how the stocks compare in terms of absolute ROIC growth.

Source: Data from YCharts.com. In percentage points.

Alexion comes in a solid first place, while Priceline edges Apple out. However, Apple is still ahead of Perrigo. So why did Perrigo take the bronze medal in our S&P Olympics?

My hunch is that it has to do with Perrigo's relative improvement. The company more than doubled its ROIC during this time frame. Of course, it could also simply be that our market judges cheated Apple out of the medal it deserved.

On to Rio
Knowing the S&P winners for the last five years doesn't help us much with determining who the winners will be going forward. However, knowing how they became winners can help us in selecting stocks that are likely to do well in the future.

Foolish investors should certainly look at which stocks are growing earnings, book value and free cash flow. Based on these past winners, though, we should also look closely at ROIC growth.

My prediction is that the S&P winners when the 2016 Olympics come around will share the same attributes of this year's winners. Examining the key growth factors mentioned above can help investors spot some of the top performers of tomorrow. Let's all enjoy the London games -- and then get ready for Rio.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.