The S&P 500 got off to a historically bad start to 2016, plunging through mid-February. But in the succeeding weeks and months, it put up so many positive performances that it's now trading near its all-time high. This huge rally has caused valuations across the board to become stretched, which means that investors looking for value are finding fewer and fewer opportunities.

Thankfully, if you're willing to scour the investing universe, there are always bargains to be found. We asked some Fool contributors to do just that, and recommend a stock that they think is a buy now. Read below to see which stocks they picked and why.

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A big catalyst on deck

Todd Campbell: Shares of Portola Pharmaceuticals (NASDAQ:PTLA) nose-dived earlier this year after management reported mixed late-stage trial results for its anticoagulant, betrixaban. However, disappointment could shift to optimism in August given the possibility that the FDA will approve its drug AndexXa on Aug. 17.

If that happens, AndexXa will be the only FDA-approved antidote for factor Xa anticoagulants. That's important, because factor Xa inhibiting drugs have been increasingly winning away market share from warfarin since Johnson & Johnson launched the first factor Xa inhibitor, Xarelto, in 2012.

An AndexXa approval would likely make this drug a must-have for emergency health providers, which means that it could be a top seller that more than justifies Portola's current $1.4 billion market cap.

Portola estimates that between 1% and 4% of patients who are treated with factor Xa inhibitors may experience major bleeding, and that an additional 1% will require emergency surgery. In the U.S. alone, the company claims that over 50,000 factor Xa treated patients were admitted to hospitals because of bleeding. Overall, Portola estimates more than 100,000 patients a year in the U.S. could benefit from AndexXa therapy. By 2020, Portola estimates that up to 500,000 patients a year could require AndexXa in the G7 countries alone.

Obviously, a FDA OK isn't a given, but since there's a need for such an antidote and AndexXa's trials were a success, I think there's a really good chance this drug gets the nod. If I'm right, then owning Portola's shares could be profitable.

A golden opportunity

Neha Chamaria: Sherwin-Williams' (NYSE:SHW) recently announced second-quarter numbers may not have painted a pretty picture, but the fall the stock took as a result offers you an opportunity too tempting to ignore.

Sherwin-Williams' muted 3% year-over-year revenue growth in Q2 didn't go down well with investors, but it isn't as bad when you consider rival PPG Industries' (NYSE:PPG) 1% revenue drop in Q2. The market also appears to have missed a key metric: Sherwin-Williams' same-store sales -- sales from stores open more than year -- climbed 5% during the second quarter and 7% during the first half. That's important to consider, given that the company is in the middle of an expansion phase. It opened 31 new stores during the first six months of 2016. Put another way, Sherwin-Williams isn't growing its revenue by increasing the number of stores, but by attracting more customers to its existing stores. That reflects the brand's power.

A man lays wooden flooring while his puppy watches.

Image source: Getty Images.

Also of note: Sherwin-Williams grew its net income almost 13% during the first half of the year. If the paint maker is doing so well now, one can only imagine the growth potential that lies ahead once it completes its acquisition of Valspar in a deal that's expected to close early next year. The purchase will substantially expand Sherwin-Williams' global footprint, and secure its position as the largest company in the industry, toppling PPG Industries. Needless to say, one quarter that doesn't meet Street estimates should matter little to shareholders of a growing company with big plans in the pipeline.

This travel stock has hit an air pocket

Brian Feroldi: Growth investors have always been willing to pay up for fast revenue and profit growth, but it only makes sense if the underlying company continues to perform well. When one of these highfliers temporarily shows signs of slowing growth, bad things tend to happen to its share price.

Such is the case right now with TripAdvisor (NASDAQ:TRIP), the leading provider of online travel reviews. Traders have been pummeling the company's stock over concerns of slowing growth for more than a year now. Shares are currently more than 36% below their all-time high.

Unfortunately, last quarter's results didn't do anything to help the situation. Revenue dropped by 3% and net income plunged by 40%, well shy of expectations. Those results sent plenty of investors running for the hills, which I think affords us a great opportunity to buy a great growth stock at an attractive price.

What Wall Street is missing is that TripAdvisor is in the middle of a massive business model shift, and that's masking its true growth. The company is currently rolling out a new "instant booking" feature across its sites that allows customers to book their travel from within TripAdvisor.

That's a smart long-term move, but it's temporarily wreaking havoc on the company's financial statements, because TripAdvisor can't recognize "instant booking" revenue until the customer actually takes the trip. That is creating about a six-month lag in revenue recognition, which is why revenue currently looks likes it's declining. At the same time, the company is spending aggressively to build it out new growth businesses like restaurant reservations and attractions.

In short, revenue is temporarily down while expenses remain elevated, which is why things look bad right now. Management expects that the company will resume its growth trajectory in the back half of the year.

I like to keep my eye on the big picture with TripAdvisor. The company's revenue last year was only $1.5 billion, a tiny slice of the $492 billion online travel market. That gives TripAdvisor a massive runway for long-term growth, so I think this is a great stock to buy at a discount.

An undervalued tech giant

Tim Green: Though shares of Cisco Systems (NASDAQ:CSCO) are up more than 90% over the past five years, the stock is still a great buy. Cisco dominates the network switching and routing markets, and it's moving toward an integrated hardware, software, and services business model that should help drive growth for years to come.

While Cisco's core switching and routing businesses are slow growing, the company is investing in areas like collaboration and security that are producing double-digit growth rates. During its fiscal third quarter, collaboration products generated $1.07 billion of revenue, up 10% year over year, while security generated $482 million of revenue, up 17% year over year. Cisco has been making acquisitions in both areas as it attempts to position itself for future.

Over the past twelve months, Cisco has generated $12.7 billion of free cash flow. After backing out the $34.9 billion of net cash on the balance sheet, the stock trades for less than 10 times this number. Factor in a 3.4% dividend yield and a healthy pace of share buybacks, and Cisco starts to look like a bargain. It's set to report its fiscal fourth-quarter results on Aug. 17, so investors won't need to wait long before getting another update on the company's progress.

An athletic stock that's taking a breather

Jason Hall: One of the great growth-stocks of the past decade is Under Armour Inc. (NYSE:UAA) (NYSE:UA).

UA Chart

UA data by YCharts

But over the past year, the hyper-growth athletic apparel and footwear company's shares have fallen more than 20% from their high, including a nearly 10% drop since it announced earnings on July 27. Frankly, that discount makes Under Armour a great buy in my book.

Sportswear — running pants, shirt, and shoes.

Image source: Getty Images.

In fairness, the recent drop is at least partly due to its more than 50% decline in profits in the most recent quarter. But frankly I think it's a mistake -- or at least short-sighted -- to get too caught up in single quarter's profit decline, especially for a company like Under Armour that's aggressively investing in a tremendous growth opportunity.

The company's SG&A expense was up 32% last quarter, higher than its 28% sales growth, but that's by design. Three numbers that really demonstrate the growth potential:

  • Footwear sales were $243 million, up 58% and only 24% of total sales.
  • International sales were $150 million, up 68% and only 15% of sales.
    • Chinese revenues will only reach $150 million for the full year.

Bottom line: Under Armour management is investing in growing its presence in footwear and international sales. Those investments are happening at a higher rate than overall sales growth, pinching profits in the short term. But looking out a few years, those investments are likely to pay off with huge returns.

Even after falling 20% from its highs, Under Armour stock isn't exactly cheap. But if it's huge growth you're looking for, now's an excellent time to buy shares.

A back-to-school winner

Steve Symington: On the heels of its fifth straight quarterly earnings beat last week, I think now is a great time to pick up shares of Netgear (NASDAQ:NTGR).

To be fair, the small-cap networking hardware company's top-line growth didn't look all that impressive on the surface. Revenue climbed just 7.9% year over year last quarter to $311.7 million. But that's largely because of declines at Netgear's lumpy service provider business unit (where revenue fell 28.3%, to $67.3 million), which the company opted to right-size early last year to bring it in line with service providers' reduced investments in wireline infrastructure.

Meanwhile, Netgear's commercial business unit enjoyed 16.9% growth, to $73.7 million. And Netgear's thriving retail business unit saw revenue climb 29.5% year over year to $170.6 million, driven by demand for both its high-margin Nighthawk routers and its popular line of Arlo wireless home security cameras. In both cases, Netgear's commercial and retail businesses bucked a seasonal trend of typically slower second quarters, and management is understandably excited as they gear up for the lucrative back-to-school season. What's more, because the service provider business tends to carry lower margins than Netgear's commercial and retail units, the company managed to outperform expectations on the margin front, and more than doubled its bottom line; adjusted net income rose 143.4% year over year to $24.1 million, and climbed 148.3% on a per-share basis to $0.72.

Over the longer-term, Netgear should be able to sustain its habit of building innovative networking products to capitalize on the growing ubiquity of connected devices and network connectivity. For investors who buy now and watch that trend play out, I think the rewards could be great.

Step right up

Sean Williams: The stock that I believe should get investors running for the "buy" button in August is none other than footwear giant Skechers (NYSE:SKX), which was absolutely pummeled in July following its second-quarter earnings report.

For the quarter, Skechers reported a profit of $0.48 per share, which was a drop from the $0.52 in EPS reported a year earlier, while revenue rose nearly 10% to $877.8 million. Wall Street had been forecasting $887 million in sales and $0.52 in EPS. Skechers blamed its weak performance on currency headwinds, a fire at a Malaysian warehouse, and a shift in its domestic wholesale business.

Now let's take a step back and really look at this. A warehouse fire is unfortunate, but it's not an every-quarter occurrence. Likewise, wholesale business fluctuations between one quarter and another aren't a big deal because the numbers still add up through the first half of the year. In fact, wholesale business sales are up 3.2% during the first half of 2016. Currency isn't a big issue, either. Currency fluctuations are beyond the control of most businesses; Wall Street and investors should be paying more attention to their underlying apples-to-apples performances. In other words, Skechers was stomped on for a set of single-quarter events.

Skechers opened 133 net stores during Q2, and now has 1,548 retail locations, most of which are outside the United States. The company is still on track to have more than 1,600 stores by the end of the year, and it'll be opening its first locations in places like Uruguay and Sri Lanka. By boosting the amount of revenue it generates from overseas markets, Skechers increases its growth opportunity and the reach of its brand, while also diversifying its sales channels against inevitable economic downturns. Best of all, free cash flow is funding the majority of this expansion, meaning Skechers isn't going neck-deep in debt to open these locations.

Skechers has also assembled a top-notch team of ambassadors who appeal to multiple generations of Americans. By focusing its marketing on relevant ambassadors, and going all-out for back-to-school season, Skechers should be able to attract healthy and consistent growth.

With double-digit sales growth expected through 2018, and Wall Street forecasting EPS of nearly $3 by fiscal 2019, I'd use this recent dip as an opportunity to lace up!

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.