The idea of investing in "value" stocks is simple enough: to buy shares of a business that are trading for less than they're worth.

But if finding, buying, and holding the market's most attractive value stocks were easy, everyone would be doing it. So to help get you started, we asked three top Motley Fool contributors to each discuss a value stock they think investors should buy before the end of this month. Read on to learn why they like Facebook (NASDAQ:FB), Kroger (NYSE:KR), and AbbVie (NYSE:ABBV).

SALE sign in a shop window

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Reports of Facebook's demise are greatly exaggerated

Steve Symington (Facebook): When shares of Facebook plummeted nearly 20% in a single day late last month, you might have thought the social-media giant had revealed crushing news indicative of a failing company. But that wasn't the case.

To the contrary, Facebook is still massively profitable and growing quickly. And keeping in mind that shares had only just climbed 36% in the three months leading up to its most recent quarterly report, the pullback merely brought Facebook stock back to levels we most recently saw in early May.

That said, the plunge was driven by two notable factors. First, its latest quarterly results were technically mixed relative to expectations; earnings per share grew 32% to $1.74, beating analysts' estimates by a few pennies. But revenue soared "only" 42% year over year to $13.2 billion, falling short of estimates for $13.4 billion. But more than that, investors balked at Facebook management's prediction that not only will revenue growth rates continue decelerating in the second half, but operating expense growth will also exceed revenue growth both this year and next.

However, the latter -- expense growth -- will be primarily driven by Facebook's efforts to improve the safety, privacy, and security of its platforms, notably including its namesake platform as well as Instagram and WhatsApp. These investments should serve to bolster Facebook's rapport with users, advertisers, and government regulators. With more than half of the world's population yet to connect to the internet, according to Facebook's Internet.org initiative, this is a crucial move that should serve to solidify the long-term health of its business.

Over the long run, I'm convinced Facebook's drop will represent little more than a blip in the radar. With its shares trading at a fair 21 times this year's expected earnings, I think it will prove to be a fantastic opportunity for patient investors to open or add to their positions.

Discount on aisle three

Demitri Kalogeropoulos (Kroger): Pessimism in the bricks-and-mortar retailing world has pushed Kroger stock to an unusually low valuation of just 10 times the past year's earnings. That's a far cry from the 20 times profit that investors had been paying back when the supermarket chain was growing sales at a robust 5% rate while boosting profits by at least 10%.

Yes, the tough selling environment has pushed revenue growth closer to 1% lately. Kroger is also expecting to post another modest earnings decline in 2018, which helps explain Wall Street's dour mood on the stock. On the other hand, the retailer is on track to capture market share for its 14th consecutive year as its popular in-store brands, like Simple Truth, continue to attract more customers.

It's not clear just how much of a negative impact the shift toward multichannel retailing will have on Kroger's long-term earnings power. But this market leader has many valuable assets it can employ in this fight, including price leadership and a large, growing base of loyal shoppers. Thus, value investors might want to take a closer look at this discounted stock as Kroger's sales rebound continues gaining steam.

A big pharma bargain

Keith Speights (AbbVie): When around 60% of a company's total revenue depends on one product that could be threatened on multiple fronts, it tends to weigh on a stock. That's what has happened for AbbVie lately. The company's fortunes hinge largely on Humira, which faces biosimilar competition in Europe later this year. A noted short-seller thinks proposed changes by the U.S. Food and Drug Administration (FDA) could further threaten Humira sales.

As a result of all of this, AbbVie stock trades at less than 11 times expected earnings -- much cheaper than most of its fellow S&P 500 members. And the company's future is much brighter than that valuation implies.

It's true that will soon Humira face biosimilar competition in Europe. However, AbbVie makes a lot more money on the drug in the U.S., where Humira shouldn't encounter biosimilar competition until 2023. As for proposed FDA changes, AbbVie CEO Rick Gonzalez thinks "there were probably more positives than there were negatives" for his company.

AbbVie claims other fast-rising products, though, with cancer drugs Imbruvica and Venclexta and hepatitis C drug Mavyret. It recently won approval for another potential blockbuster, endometriosis pain drug Orilissa. AbbVie's pipeline has also been ranked as the second best in the industry.

The big pharma company should be able to generate strong growth even with challenges for Humira. I think those growth prospects, combined with a solid dividend yield of over 4%, makes AbbVie a great value stock to buy in August.

The bottom line

There's no way to absolutely guarantee that these three stocks will go on to outperform the broader market. But whether we're talking about Facebook's massive pullback last month, industry pessimism driving Kroger to mouthwatering levels, or AbbVie's growth potential and high yield, we like their chances of doing just that.

Demitrios Kalogeropoulos owns shares of Facebook. Keith Speights owns shares of AbbVie and Facebook. Steve Symington has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Facebook. The Motley Fool has a disclosure policy.