As a 40-year-old investor, your investment horizon likely spans a couple of decades until retirement, and then hopefully more decades more after you retire. One of the best ways to make use of this ultra-long-term timeframe is to buy and hold great companies with multi-decade growth opportunities. These types of businesses can generate multibagger returns and turbocharge the overall performance of your portfolio.

The challenge, of course, is identifying these companies early in their growth cycles. Fortunately, I believe I've found one outstanding business that just might fit the bill. Read on to learn more about it.

A compass pointing towards the word growth.

Image source: Getty Images.

A massive growth opportunity

There are more than 770 million internet users in China, according to Statista. That's up from 564 million in 2012 and 210 million back in 2007.

Yet while the number of Chinese internet users exceeds the entire population of the United States, it represents only about 55% of the 1.4 billion people living in China. That's in sharp contrast with the internet penetration rates in the U.S. and much of the developed world, which typically reach into the 80% to 90% range. I expect these figures to converge over time, as hundreds of millions more Chinese citizens begin using -- and shopping on -- the internet in the coming years.

In turn, e-commerce companies in the world's most populous nation are likely to enjoy strong tailwinds as this megatrend plays out. And one company stands to benefit perhaps more than any other: JD.com (NASDAQ:JD).

Strengthening -- and underappreciated -- competitive advantages

JD.com's stock is overlooked by many investors who often see it as the runner-up to Alibaba (NYSE:BABA) in Chinese e-commerce. But while it's true that Alibaba is currently the 800-pound gorilla in this massive market with a 51.3% share, according to data from Analysys International Enfodesk, JD.com has been steadily gaining ground on its larger rival. In fact, eMarketer notes that JD.com's share of retail e-commerce sales in China rose to 32.9% in the second quarter of 2017, up from 17.7% in 2014. Alibaba's market share, meanwhile, declined from 54.6% during this same time.

JD.com is winning over Chinese consumers with a multipronged approach. First, unlike Alibaba, which acts primarily as a marketplace in which third-party merchants can sell their wares, JD.com operates as a retailer -- by selling goods directly to its customers -- in addition to operating a third-party fulfillment network. This gives JD.com an edge in terms of ensuring the quality and authenticity of its goods, while Alibaba has struggled with counterfeit product issues.

Secondly, JD.com has forged partnerships with powerful allies. Chinese social media titan Tencent owns about 20% of JD.com, and has integrated JD.com's marketplace into WeChat, the dominant social app in China with more than 1 billion monthly active users. Retail colossus Walmart owns 12% of JD.com, and the two companies have merged some of their membership and fulfillment systems. And search giant Alphabet recently took a $550 million stake in JD.com, with the two companies agreeing to partner on e-commerce initiatives in China and other areas of the world. These alliances are just a few of the many deals JD.com has struck in recent years, and investors can expect more of the same in the future.

An attractive price

Even as JD.com continues to strengthen its competitive position, its stock price is down about 9% over the past year. Shares can now be had for less than one times sales and 32 times Wall Street's forward earnings estimates for 2019. That's quite a deal for a competitively advantaged business that's projected to grow its sales by more than 30% this year and 26% in 2019.

Investors appear to be placing too much emphasis on short-term profitability, which has been weighed down by JD.com's heavy growth investments. But the company is making the smart choice to sacrifice near-term profits in order to create greater long-term value for both customers and shareholders. Specifically, by spending money now to build out its best-in-class fulfillment network, JD.com should be able to offer faster and cheaper shipping than Alibaba or any of its other competitors. That's another powerful competitive advantage in a Chinese e-commerce market that's expected to grow by about 20% annually over the next half-decade.

All told, few businesses have better long-term growth prospects than JD.com. The company stands to benefit from rising internet usage and the growth of e-commerce in China, as well as the overall expansion of what will likely become the world's largest economy in the coming decades. As such, JD.com fits well with a 40-year-old investor's time horizon. And with its stock currently trading for a bargain price, investors who buy shares today should be well rewarded in the years ahead.

Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Joe Tenebruso has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), JD.com, and Tencent Holdings. The Motley Fool has a disclosure policy.