Heading to the beach, your favorite vacation spot, or your backyard this month? Don't forget to take along some reading material. Summertime is a great time to research stocks, including these top picks from five of our favorite Motley Fool contributors. Here's why August could be the perfect time to add MongoDB (NASDAQ:MDB) , Vail Resorts (NYSE:MTN), Ollie's Bargain Outlet (NASDAQ:OLLI), Cleveland-Cliffs (NYSE:CLF), and Netflix (NASDAQ:NFLX) to your investment portfolio.

A data disruptor 

Keith Speights (MongoDB): You're surrounded by data. Every online purchase you make. Every item you buy in a brick-and-mortar store. Every streaming TV show you watch. Every social media post you make or read. Pretty much everything you do today involves data. And it all has to be stored in a database somewhere.

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There's a problem, though. Most of the databases in use today were designed decades ago. They weren't built for the kinds of unstructured data that is most prominent now. They were intended to run only on a server in a company's data center rather than the cloud (for a good reason, since the cloud hadn't been invented yet). 

Enter MongoDB. The company's name means humongous database, with "mongo" embedded in the word "humongous." Unlike most of the big databases used today such as Oracle and Microsoft SQL Server, MongoDB was built from the ground up to support massive amounts of both structured and unstructured data. It was also designed to run anywhere, including servers in on-premise data centers and in the cloud.

MongoDB's founders were the team behind internet advertising company DoubleClick, which was acquired in 2007 by Google (now a subsidiary of Alphabet). After selling DoubleClick, they set out to create a database that addressed all the shortcomings of other databases they used while they were in the internet advertising business. They also took a much different path to commercialization -- a path that has helped turbocharge MongoDB's growth.

In 2009, MongoDB was released as open source. That means the database's source code was made available at no cost to developers. Giving their database away for free might sound like a really dumb way to run a business. But there's more to the story.

Only a limited version of the database is free. For organizations that need more features and need ongoing support, there's a charge. This "freemium" model has worked very well for MongoDB. By 2016, its database had been downloaded over 20 million times. The following year, the number of downloads jumped to over 30 million. Now, MongoDB's database has been downloaded over 60 million times.

And the company's revenue has skyrocketed. When MongoDB reported first-quarter results in June, its revenue totaled $89.4 million, up 78% year over year. What's especially impressive is that growth continues to accelerate. In the previous sequential quarter, revenue increased by 71% year over year. The great thing is that MongoDB makes most of its money from subscriptions -- recurring revenue that it can count on coming in each month.

MongoDB now has 14,200 customers and counting. That's more than double its number of customers from just a year ago. It makes at least $100,000 annually from nearly 600 of those customers, up from less than 400 in the prior-year period. 

MongoDB hasn't even scratched the surface of its potential. Even with its tremendous growth, the company has less than 1% penetration of the database market. This data disruptor looks like a great stock to buy in August and hold for the long run.

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Think snow

Dan Caplinger (Vail Resorts): Summer might sound like exactly the wrong time to buy shares of a ski resort operator. But Vail Resorts has just come off a great winter, and it hasn't taken a summer vacation from looking for further opportunities for growth.

Vail Resorts operates some of the best known ski resorts in the world. Among its portfolio of top U.S. properties are the Vail, Beaver Creek, Breckenridge, and Keystone resorts in Colorado; Heavenly, Northstar, and Kirkwood in Lake Tahoe; and Park City in Utah. Vail also has the prominent Whistler Blackcomb resort just north of Vancouver in British Columbia, as well as the Perisher resort in Australia and some properties in the U.S. Midwest.

Coming off two subpar winter seasons, the winter of 2018-2019 was a huge growth story for Vail Resorts. In its fiscal third quarter, which covers late winter and early spring, Vail saw revenue and income growth of double-digit percentages, with lift revenue seeing even stronger gains. Vail also gets a substantial portion of its revenue from providing lodging to visitors, and 17% growth for the lodging segment showed just how popular Vail properties were during the long winter. Extraordinarily good snow conditions lasted well into the spring, giving the resort operator a much-needed break from disappointing performances in prior years.

Also helping its growth has been Vail's acquisition strategy. Its purchase of the Stowe Mountain ski resort in Vermont in 2017 helped give it more East Coast exposure, and it's consistently been on the hunt for ways to extend its reach.

Vail's most recent strategic move is why it's my pick this month. Vail just announced that it would buy out competing ski resort operator Peak Resorts in a deal worth $264 million. Peak operates a network of ski properties across the country. In the Northeast, Vail will acquire 10 properties, including Mount Snow in Vermont, Hunter Mountain in New York, and three resorts in New Hampshire, and five locations in Pennsylvania. Peak also has another seven resorts spread across the Midwest in Ohio, Indiana, and Missouri.

Vail has high hopes that the move will give it more access to major metropolitan areas. In particular, New York and Boston will benefit greatly from its New England, New York, and Pennsylvania locations, while its Midwest locations should enhance the efforts that Vail has already made in trying to attract visitors from Chicago and Detroit.

Even better, adding new properties will make Vail Resorts' Epic season passes more valuable. Epic gives skiers the ability to get unlimited, unrestricted access to resorts across the company's network, and so the bigger that network is, the more valuable the season pass becomes to many customers. In addition, Vail will not only honor Peak Resorts season passes but will also extend the right to upgrade those passes to Epic status.

Skiing is a lucrative business, and Vail Resorts has capitalized on the big opportunities in the industry. By continuing to build out its network of high-quality resorts, Vail is giving its customers value they can't get anywhere else -- and shareholders are in a great position to benefit from it.

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Good stuff, cheap

Todd Campbell (Ollie's Bargain Outlet): The slopes aren't the only thing forward-thinking investors ought to be focusing on right now. The hot summer months are also a great time to buy retail stocks ahead of back-to-school and holiday shopping. A general lack of interest in retailers during summer can create opportunities to pick up shares at bargain prices, particularly in retailers that benefit from e-commerce threat, such as Ollie's Bargain Outlet.

If one of the marts is selling something for a dollar, we want to sell it for fifty cents, and we want to pay a quarter.

-- CEO Mark Butler

Ollie's Bargain Outlet is a 330-store chain specializing in the mistakes of manufacturers, distributors, and other retailers. The company's shelves are packed with products it's picked up cheap because of overstocked inventories, discontinuations, or store closures. For instance, Ollie's profited handsomely when Toys R Us went under last year, snapping up toys to sell in its stores, as well as 18 former Toys R Us locations.

Moving quickly to keep its stores full of great buys has created an enviable, loyal following among its customers, including 9.4 million members of its rewards program. Those members, affectionately called Ollie's Army, can get discounts of up to 30%, depending on their spending, and they represent about 70% of Ollie's total sales. These so-called "bargainauts" spend about 40% more than non-Ollie's Army members. 

Last quarter, Ollie's retail sales grew 18% year over year and thanks to operating leverage, net income increased 27%. Same-store sales were up 0.8% in the quarter, but it wasn't just repeat business that drove revenue higher. Sales also benefited from a higher store count. Because Ollie's only operates in 23 states, it can open new stores (including 21 stores last quarter) without cannibalizing its existing locations.

How big could Ollie's get? It's hard to say, but I think a good answer is: much bigger than it is today. When it went public in 2015, it commissioned a study that determined the U.S. could support 950 locations based on its existing customer demographics. Ollie's CEO thinks that figure could be too low. In a recent interview with The Motley Fool, he suggested that the 1,400 to 1,500 stores operated by Big Lots may be a better proxy.

In fact, Ollie's isn't even anywhere near close to oversaturating key markets it's already operating in, including Texas. Currently, it has only four stores there, but Butler thinks Texas could support 80 to 100 stores someday. It's only early innings for the company in key markets like New York and New England, too.

Importantly, management's new store strategy is measured. The goal is for mid-teens store opening growth annually, an approach that can help it reduce the risk of picking bad locations while providing a tailwind for sales growth long into the future. Furthermore, because it limits store expansion to adjacent markets, it's able to tap into brand recognition to help insure each new store is a success.

I'm also a fan of its CEO, who has been with the company since the beginning. Butler's learned from some of the best discount retailers in the business and he's got 37 years of experience backing up his decisions. It also doesn't hurt that he's the largest single individual owner of Ollie's shares, suggesting his interests are aligned with investors.

If loyal customers, runway for growth, and stable management aren't convincing enough, consider this final point: Ollie's stock is down about 14% since April, making its own stock a relative bargain right now.

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Buy an iron ore producer in the late innings of economic expansion? Are you insane?

Tyler Crowe (Cleveland-Cliffs): I will be the first to admit that it's absurd to consider a business as sensitive to the economy as iron ore is when we just broke the record for the longest economic expansion period in U.S. history. It seems even crazier when there are signs that economic growth is starting to stall. 

But hear me out.

Cleveland-Cliffs is a company that investors should have on their radar right now. It's a perfect combination of a business that doesn't get enough credit for its business plan, a management team that has proven itself more than capable to generate shareholder value and a criminally undervalued stock price. 

Four years ago, this was a disaster of a company. It was a sprawling miner making huge acquisitions at the peak or the commodities gold rush around 2010 and a bloated balance sheet. When current management took the helm, it went about stripping the company down to its most profitable business -- U.S. iron ore -- and cleaned up the balance sheet. 

Thanks to those moves, it has drastically reduced its leverage -- its debt-to-EBITDA ratio is down from 9.0 to 3.2; it's generating solid profit margins; and it's generating lots of free cash flow to give back to shareholders. In the past year alone, management has been able to reinstate a dividend and repurchase 10% of shares outstanding. 

What's even more encouraging is that management is investing in a new iron ore upgrading facility that will significantly improve its profitability and mitigate its sensitivity to the market cycles for iron ore. Here's how CEO Lourenco Goncalves described how the company is better prepared for the next downturn in domestic steel production on the company's most recent conference call. 

First, with the addition of our HBI [hot briquetted iron] plant, we have created new demand for almost 3 million long tons of pellets per year. This new demand will, in good times, tighten the market and in bad times, provide us with volumed certainty, while paying ourselves at a healthy margin. Second, our new pellet contracts have more take-or-pay components that minimize nomination reductions, providing us with another layer of protection. Third, we now have more optionality and product flexibility. We can make a standard, fluxed, super flux and DR-grade pellets. We can access both the EAF [electric arc furnace] metallics market or the traditional blast furnace market with quality specs for the full spectrum of needs.

Even though Cleveland-Cliffs has done all these things to better position itself in the market and is generating loads of cash for investors, its stock still trades at a price-to-earnings ratio of 2.7 times. 

Yes, buying a mining company like Cleveland-Cliffs is normally a bet on a long economic expansion and that may or may not be in the cards. Management foresees good times for the market in the short to medium term, though, and for years they have been very good at gauging where the wind will blow in the iron ore market. All of this together adds up to a stock that investors should seriously consider right now. 

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Don't miss this rare buy-in window

Anders Bylund (Netflix): The global leader in streaming video services has rarely looked as tempting as it does right now.

The company fell short of management's guidance for subscriber additions in July's second-quarter report. The domestic segment actually lost more customers than it added during the quarter, which had never happened before. Overall, projections for 5 million net new accounts were thwarted by an actual result of 2.7 million additions.

The market reaction was brutal. Netflix shares closed 10.3% lower the next day. As of July 23, Netflix traded more than 20% below its 52-week highs.

That's a big mistake. Mr. Market has opened a fantastic buy-in window for this incredible stock.

Sure, Netflix's torrential subscriber growth hit a speed bump in the second quarter. Management underestimated the limiting impact of recent price increases in America and a few overseas territories. Furthermore, I would argue that seasonal effects played a large role here. The second quarter is always Netflix's slowest-growth period of each fiscal year, and the company has missed its subscriber additions guidance for this period in three of the last four years.

Business as usual, in other words.

And that's not all. Earnings came in well above expectations as Netflix pushed a hefty chunk of its marketing budget from the second quarter to the third. That's another growth-slowing detail to consider. Despite all these obstructions, Netflix still posted that 2.7 million subscriber boost and a 22% year-over-year increase. Meanwhile, revenues surged 26% higher as those price increases started to take effect.

It is true that the streaming video market is teeming with new and looming competition such as Disney+ and HBO Max, but those are more likely to widen the total market than to take subscribers away from Netflix. We're looking at a classic overreaction to a single disappointing metric, which is sure to rebound in the third quarter and beyond.

That's why I'm downright excited about the current opportunity to invest in Netflix. Buy now and thank me later, like you did in 2011 and 2016. For those keeping score at home, those recommendations have posted returns of 2,700% and 180%, respectively.