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While the riskiest of stocks are often the ones that provide investors with amazing returns, the downside is the very real possibility of a permanent loss of capital. For every high-flying growth stock, there are many more that collapse, wiping out investors in the process.

For investors unwilling or unable to stomach this risk, there are still a few options that will allow for sound sleep in lieu of the potential for massive gains. Verizon (NYSE: VZ), Pfizer (NYSE: PFE), and ExxonMobil (NYSE: XOM) are three stocks that our Foolish contributors believe are well-suited for low-risk investors.   

Tim Green (Verizon): While there are no guarantees in the world of investing, Verizon is a good option for those averse to risk. The company is the largest wireless carrier in the country, with 110.8 million wireless connections at the end of the third quarter, and its wireless service is routinely rated as the highest-quality option.

AT&T is the only other major player, with Sprint and T-Mobile having smaller subscriber bases. Building out and maintaining a wireless network is extremely capital-intensive: Verizon has spent $27 billion on capital expenditures over the past 12 months, for example. This enormous cost makes scale a big advantage in this business.

While the U.S. smartphone market is mostly saturated, meaning growth from Verizon's wireless business will be fairly muted going forward, the company is investing in new initiatives. Verizon recently launched an ad-supported mobile video service, Go90, with the ultimate goal of leveraging the vast amount of subscriber data maintained by the company. Advertising and data will be the drivers of growth for Verizon in the future.

Verizon's growth will likely be slow going forward, but the company's dominance in the wireless business makes the stock a fairly safe bet. The stock isn't all that expensive, with analysts expecting nearly $4 per share in earnings in both 2015 and 2016. This puts the P/E ratio at roughly 11, and with a dividend yield just shy of 5%, low-risk investors are getting a pretty good deal.

George Budwell (Pfizer): Among healthcare stocks in general, and pharma stocks in particular, there are few rock-solid safe havens for investors these days. 

I think Pfizer is probably your best bet if you're looking to capitalize on the trend of aging America and increased spending on healthcare. I like the stock right now because the company's innovative products business has been posting impressive levels of growth, driven by newer medicines like the breast cancer drug Ibrance, the blood thinner Eliquis, and the pneumonia vaccine Prevnar 13. 

Although the drugmaker's established products business continues to act like an anchor on its earnings, management's desire to pair up with the specialty pharma Allergan (NYSE: AGN) could change this situation in a hurry. 

What we are likely to see is Pfizer break off its innovative products into the Allergan family of products, and subsequently launch a generic drug business. Presumably, current shareholders would receive a stake in both businesses, but the one that's most attractive would obviously be the combined Allergan-Pfizer entity. Based on how Pfizer's innovative business is performing so far, I believe the Allergan-Pfizer business could realistically post 20%-plus growth on its top line for several years moving forward. 

But even if this merger doesn't come to pass, Pfizer still offers investors one of the highest dividend yields in the sector and a projected 5-year CAGR for its EPS of nearly 8%. So, I find this Big Pharma to be one of the more attractive stocks in the healthcare sector, and perhaps one of the safest investments as well. 

Matt DiLallo (ExxonMobil): Warren Buffett famously quipped that it is "only when the tide goes out do you discover who's been swimming naked." In the energy industry, that tide was the price of oil. In falling from its peak north of $100 a barrel to recent lows in the $40 per barrel range, it has exposed a number of oil companies that were overexposed to debt.

That said, it has also made it pretty clear that ExxonMobil is a picture of modesty. Exxon has the best balance sheet in the entire energy space, with a Triple-A credit rating and low leverage.

Source: ExxonMobil Corporation.

Because of this low leverage the company hasn't been scrambling to sell assets to pay down debt. Instead, Exxon built up a war chest of cash, which could be used to take advantage of the situation.

The other factor that really makes Exxon a low-risk stock compared to the rest of the industry is its focus on driving peer-leading returns, even if the upside is a little more limited.

XOM Return on Equity (TTM) Chart

XOM Return on Equity (TTM) data by YCharts.

Because of this focus, Exxon has avoided investing in borderline projects just to drive growth, which has really paid off, as those projects would have been under a lot of pressure now that prices have plunged.

Exxon knows the oil and gas business is risky enough; that's why it only uses a modest amount of debt and focuses on returns over growth. These two factors are what make Exxon a great stock for investors who don't like risk, but still want some energy in their portfolios. 

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.