Freeport's Chino property in New Mexico. Image source: Freeport-McMoRan.

The stock market has had to work hard for its gains in 2016, surviving a correction early in the year to post a modest gain year to date. Yet even as major market benchmarks start to approach record levels, the S&P 500 is up just 4% or so in 2016. In a sluggish market environment, it becomes even more important to identify promising individual stocks in order to boost your overall returns. With that in mind, looking at what has proven successful so far this year can be a good starting point for understanding how to find tomorrow's top performers. Let's turn to three top-performing stocks this year to see if there's any opportunity for further gains for new investors.

Freeport-McMoRan

The plunge in commodities prices over the past several years has dealt a double blow to Freeport-McMoRan Inc. (FCX 2.40%). Historically, the company focused on mining copper, gold, and molybdenum, and the drop in gold prices earlier in the decade had a profound negative impact on its business. In an effort to diversify, Freeport decided to acquire oil and gas exploration and production companies, but that proved to be an ill-timed enterprise. The subsequent plunge in energy prices has also pulled down copper along with it, and the combination caused a big drop in Freeport's share price in 2015.

In 2016, two things have helped push Freeport up roughly 65% year to date. First, energy prices appear to have stabilized and have regained much of the ground they lost in the opening months of the year. Second, gold prices have climbed in response to growing concerns about the health of paper currencies, and that has lent some support to the flagging copper market as well.

Freeport has done a good job of cutting costs, and if oil stops falling, then the company won't have to keep taking massive asset impairment charges against its energy business. With oil just now getting back to $50 per barrel, Freeport has more upside if the commodities markets stay favorable.

Silver Wheaton

Like gold, silver prices have taken a huge hit since their highs in the early 2010s, when bullion approached $50 per ounce. Silver Wheaton Corp. (WPM 2.23%) suffered as a result of that decline, primarily because the silver-streaming specialist relies on a continuing flow of precious metals, from its streaming arrangements with mining-company partners, to generate revenue and profits. By financing projects and taking the right to purchase the produced metals at bargain prices, Silver Wheaton gets most of the upside from potential price rises without much of the risk of conducting its own mining operations.

The current $16 per ounce that silver fetches is a far cry from the best of times, but so far in 2016, Silver Wheaton has seen its stock rise by two-thirds because of silver's modest rebounds. In addition to its direct benefits from rising bullion prices, Silver Wheaton has also aggressively taken advantage of the tough environment to enter into new streaming arrangements with partners with attractive terms. By tapping into gold as well, Silver Wheaton has gone beyond its namesake white metal to find the best deals. That's something that should keep generating positive results well into the future.

Computer Sciences

Market dynamics often justify share-price rises, but in the case of Computer Sciences Corp. (CSC), there's a much simpler answer: mergers and acquisitions activity. The company is up almost 60% so far in 2016, and most of those gains have come in just the last month.

In late May, Computer Sciences said that it would merge its business into the enterprise-services division of Hewlett Packard Enterprise Co. The deal should close in the second quarter of 2017, combining the two business units in roughly 50-50 proportions. Computer Sciences had been working to grow its business both organically and through acquisitions, but the scale of the companies that Computer Sciences had acquired was tiny compared to bringing on HP's business. HP and Computer Sciences have been business collaborators for years, and so formalizing the arrangement effectively lets the two companies gain full advantage from synergies and other potential benefits.

When markets are flat, stocks that can post 50% price gains in less than half a year are impressive. Although much of the potential gain from the Computer Sciences merger with HP is likely backed into the stock already, further rises in copper, gold, silver, and crude oil could help both Freeport-McMoRan and Silver Wheaton keep climbing.