When it comes to investing in the stock market, simplicity is key. Owning companies that have a track record of success is a good place to start, but finding stocks that also have a long runway for expansion in the years ahead is even better. 

Add Warren Buffett's favorite characteristic, an economic moat, to the equation, and you're on your way to building a winning portfolio. And thanks to the ability to purchase fractional shares, even small amounts of cash can be put to work in the stock market. 

With that being said, here are three stocks you can buy with $700 right now. 

Hand holding several hundred-dollar bills.

Image source: Getty Images.

Professional contractors' best friend 

As the world's largest home-improvement retailer, Home Depot (NYSE:HD) generated a record-breaking $41.1 billion in sales last quarter, which was an increase of 8.1% from a difficult comparison in Q2 2020. About 45% of revenue comes from the company's professional customer base, boosting Home Depot's prospects because this valuable group spends more and visits stores more frequently than do-it-yourselfers. These contractors need a mission-critical supplier partner that can provide the right tools and supplies in a timely manner, and Home Depot is there to deliver. 

"We've seen our Pro business strengthen for several quarters in a row with the last two quarters where the Pro outperformed the DIY customers for the first time since the pandemic started," CEO Craig Menear highlighted on the recent earnings call. As a direct result of the strong housing market, consumers are taking on bigger renovation projects because they view it as an investment in their homes. And the popularity of remote work, driven by the pandemic, will only lead more people to reassess their living situations, supporting demand for this leading retailer's products. 

For a reasonable forward price-to-earnings ratio of 23, investors can buy shares in a top-notch company that is fundamental to the American economy. 

Driving the athleisure trend 

Neither NikeAdidas, nor Under Armour can claim what this company has done. Lululemon Athletica (NASDAQ:LULU) made it fashionable to wear athletic gear for comfort before any of its rivals, and this initial strategy has resulted in the stock soaring more than sixfold over the past five years. 

Today, the company not only has a powerful market position when it comes to women's apparel, but Lululemon's men's business is booming. On a two-year stacked basis (to account for the pandemic's effect), the men's segment grew sales at 31% per year, compared with a 26% rate for women's. And Lululemon has big ambitions overseas, opening the majority of its new stores this fiscal year in international markets. 

Person in yoga pants is lying on sofa and holding mug.

Image source: Getty Images.

During the most recent quarter, direct-to-consumer revenue accounted for 41% of the overall business. And this is a key differentiator from competitors, who depend heavily on third-party sporting goods retailers to push merchandise. This also supports the company's brand image by helping Lululemon avoid price markdowns. 

Don't avoid the stock just because it trades at a premium multiple of 57 times next year's earnings. Wall Street analysts are forecasting profit to more than double over the next three years, giving investors plenty of growth to cheer about when it comes to this outstanding company. 

The definition of recession-proof 

Since at least 1995, O'Reilly Automotive (NASDAQ:ORLY) hasn't posted negative revenue growth in any year, demonstrating just how resilient this aftermarket parts retailer is. In fact, during the mortgage bust and ensuing recession, sales increased 42% in 2008 and 36% in 2009. In positive economic times, consumers are more inclined to ditch their old vehicles and purchase new cars. And in recessionary times, people will do whatever they can to extend the life of the automobiles they own. All of this benefits O'Reilly and makes it a sound all-weather stock to own. 

In the most recent quarter, same-store sales jumped 9.9%, and this was after growing 16.2% in the year-ago period. O'Reilly might be a boring and often-overlooked business, but its stock has historically been a market winner. Management has also cut the share count in half over the past decade, further fueling investor returns. 

Like Home Depot, this is a retailer that has so far defended itself from the threat of e-commerce, and I believe it will continue to do so due to the fact that customers need products urgently to go about their days. Even Amazon can't compete with O'Reilly's robust distribution network, consisting of more than 5,700 stores in the U.S. 

O'Reilly's stock is selling today at 22 times forward earnings, which is in line with the broader S&P 500. But this business is meaningfully better than the average company out there, so buying shares today would definitely improve the quality of your portfolio. 

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.