So far, 2016 has been an extremely challenging year for stock market investors, providing plenty of "opportunities" to make the wrong move with your money. That's the bad news.

The good news is that there have been just as many opportunities to make the right moves. As I write, more than 25% of the S&P 500 is up 10% or more year-to-date. But to pick the outperformers consistently, you need an edge. And one simple metric could give you a huge edge in 2016.

Historically, looking at this straightforward stat has been enough to double the returns of the S&P 500 index. What's the secret to outperforming the S&P by double? Just focus on companies that are sharing the most cash with shareholders.

You might think I'm talking about dividends here, but they're only part of the picture. Instead, the metric we're talking about is actually something called "shareholder yield."

Shareholder yield is made up of anything that directly returns cash or equity to your portfolio. Yes, that includes obvious moves such as dividends -- but it also includes share buybacks and paying down debt.

Any of those three corporate actions can unlock significant value for shareholders, and the data backs it up. According to research by James O'Shaughnessy, over a 40-year period, large-cap stocks with the highest shareholder yield delivered average gains of 18.05%. That's almost double the average annual returns that investing in the big S&P 500 index would have earned you.

With low interest rates and record levels of cash sitting on corporate balance sheets, management teams are looking for the most effective ways to return value to shareholders. It's not one size fits all, either; the best mix varies from company to company. But by looking at the trifecta of dividends, buybacks and debt extinguishment, you can be sure that you won't miss out on any of the proceeds.

With that in mind, here's a look at five stocks that have provided superior shareholder yield in the last year.

Nordstrom

Leading things off is high-end department store Nordstrom  (JWN - Get Report) . So far, 2016 has been a pretty quiet year for this retailer. Shares are up 2.2% on a total returns basis, edging out the S&P's slightly in the red positioning by a small but meaningful margin. And that could be just the start of things for this stock as luxury spending holds up for the rest of the year.

Nordstrom operates approximately 300 stores under the Nordstrom and Nordstrom Rack banners and also owns the HauteLook and Trunk Club brands online. Nordstrom's core market is made up of "mass affluent" consumers. By targeting the higher end of the income scale, the firm has insulated itself from much of the squeeze on the middle market that's harangued more mainstream department store rivals in recent years.

Nordstrom's lower store count than other large chains is a product of scalability. The firm's stores do exceptionally well in affluent areas and less well elsewhere. The introduction of innovative online shopping brands should help to offset the brick-and-mortar growth challenges at Nordstrom.

Not all of Nordstrom's exposure is on the high end of the retail spectrum. The Nordstrom Rack chain, which sells off-priced brand-label merchandise, is a major asset for the greater Nordstrom enterprise. That's because, while competitors end up selling excess inventory at fire sale prices to other off-price stores, Nordstrom is able to keep those sales in-house, recouping a bigger chunk of revenues while still not competing with the firm's full-price stores.

Nordstrom has been an excellent steward of shareholder capital in the last year. Between more than $2 billion in dividends and buybacks and a $328 million debt reduction, Nordstrom has offered up a 30.8% shareholder yield in the last year.

Best Buy

Another retail stock that's paying out a huge shareholder yield right now is electronics store chain Best Buy  (BBY - Get Report) . In total, Best Buy paid out a 17.6% shareholder yield in the last four quarters, spread between dividends, buybacks and debt reduction. In total, it amounted to $1.74 billion returned to shareholders in some shape or form in the last year.

Best Buy is a turnaround story. The firm is the biggest electronics retailer in the world today, a position it earned by outliving all of its peers; the firm has more than 1,700 stores today. Best Buy's big advantage comes from that store footprint. At the same time, online rivals such as Amazon.com  (AMZN - Get Report)  have been investing in huge delivery infrastructure, Best Buy has been waking up to the fact that it can offer similar consumer reach, in many cases by adding new distribution features such as ship-from-store fulfillment from its Web site.

Best Buy is finally looking cheap. The firm has managed to cut billions of dollars from its cost structure, and it's been consistently profitable since 2014. Just as important, 15.7% of Best Buy's market capitalization is paid for by net cash on its balance sheet. After a long stretch of underperformance, shares are finally starting to catch a bid again in 2016: Best Buy is up 16% from its lows back in January.

Western Digital

Western Digital  (WDC - Get Report)  has been paying out a hefty shareholder yield of its own in the last year: So far, the firm has handed $1.4 billion in cash back to shareholders, primarily through share buybacks. That's been cold comfort to shareholders lately; Western Digital's share price has plummeted by 54% in the last year. But that big cash return in the trailing year makes WDC statistically predisposed to outperformance in 2016 after shares' recent selloff.

Western Digital is one of the biggest hard drive makers in the world. About 60% of revenue comes from sales to original equipment manufacturers, while the rest comes from distributors and retailers. The replacement of the hard disk drive as the storage medium of choice for computers has been a major headwind for Western Digital, and the firm has been working hard to shift its exposure over to faster solid-state drives and hybrid drives. The pending acquisition of SanDisk  (SNDK)  is a major step in that direction -- Western Digital is paying $78 in cash and stock to acquire the SSD giant, a move that will dramatically shift Western Digital's exposure to the new tech and enable it to leverage its distribution to move memory.

Even after the merger, it's important to realize that hard drive storage will continue to be an important piece of the combined business for Western Digital, particularly in emerging markets and other applications where cost trumps speed. Shares are trading at a deep discount right now -- but between a substantial shareholder yield payout and the pending SanDisk merger, this stock could be about to make up for lost time from a performance standpoint. Look for the merger closing as an important upside catalyst in Western Digital.

Delta Air Lines

Plummeting oil prices and supply constrained travel markets have created a perfect storm of profitability for airline operators such as Delta Air Lines  (DAL - Get Report)   -- and management has been sharing that surge in cash with shareholders. In the last year, Delta had handed $4.27 billion in cash back to investors, almost half of which came in the form of a $2.2 billion stock buyback operation. Debt extinguishment and buybacks made up the balance of the shareholder yield story at Delta.

Delta is one of the biggest airlines in the world, with 809 aircraft in its fleet serving about 250 mainline destinations worldwide. It's also one of the best-run airlines. The firm's decision to save costs by maintaining an older fleet, on average, than competitors has paid off as lower jet fuel costs have offset higher fuel consumption of the older aircraft. The firm does realize that this environment won't last forever, so it's leveraging its strength now to upgrade its fleet with newer planes while interest rates are low and the firm has bargaining power.

On the service side of the spectrum, Delta made an important change recently, when it introduced a system of racking up frequent flyer miles based on dollars spent rather than trip length. That system rewards Delta's most lucrative passengers with perks and should go a long way in making sure that the top spenders are the ones getting the most redeemable benefits.

Earnings on Thursday are an important potential catalyst in Delta; the firm has beaten Wall Street's earnings targets in 11 of the last 12 quarters.

TheStreet's Jim Cramer recommended buying Delta over JetBlue (JBLU - Get Report) .

T. Rowe Price Group

The trajectory is looking more attractive at Baltimore-based fund manager T. Rowe Price Group  (TROW - Get Report) . On a total returns basis, this stock has been outperforming since shares bottomed back in early January, up 14% in that stretch. As the broad market goes, so goes T. Rowe -- the relative attractiveness of the investing environment is what drives cash to flow into T. Rowe's funds.

T. Rowe Price is one of the biggest asset managers in the country, with $763.1 billion in assets under management at the end of last year. Most of that is in retirement funds; retirement accounts add up to about two-thirds of total managed assets, making this financial firm heavily leveraged to the ebb and flow of the value of retirement accounts. As more millennials, the biggest generation to date, put more assets into retirement accounts, T. Rowe Price's retirement date funds should continue to attract investible dollars (and management fees).

Reputation is a critical part of T. Rowe Price's success. The firm is known for a risk-averse bent to its strategies, in no small part because of its retirement focus. That approach has also led to important outperformance over the long-term: close to 80% of T. Rowe Price's funds are outperforming the rest of the industry on a 10-year time horizon. That long-term outperformance is an asset that's not easily replicated by rival fund managers.

Meanwhile, management has been paying back the firm's own shareholders. In the last year, T. Rowe Price returned $2.05 billion to investors in the form of dividends and buybacks, an 11.45% shareholder yield in total.

That stat makes this asset manager more likely to keep outperforming in 2016.

Disclosure: This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.