Just when you think Amazon.com (NASDAQ:AMZN) shares may have peaked, they keep going. After a 23% gain in 2019, the stock is up 13% so far this year, pushing the online retailer's market capitalization above $1 trillion. The shares are now trading at a record high. Amazon Chief Executive Officer Jeff Bezos even locked in profits recently, selling $1.84 billion in shares. (But not to worry: Bezos has said in the past that he generally sells about $1 billion in Amazon shares annually to fund his start-up, Blue Origin.)

Though Wall Street remains bullish on Amazon stock, with average expectations for 14% upside over the next year, investors who haven't yet bought the shares might wonder if it's too late to bet on the Amazon story -- at least at the stock's current level. Let's take a closer look.

Strong revenue and earnings results

Amazon's annual revenue and profit have been growing steadily since 2015. In the company's recent earnings report, the online retail giant said net sales rose 20% to $280.5 billion in 2019. Amazon's fourth quarter earnings per share of $6.47 far surpassed the average analyst estimate of $4.03.

A miniature shopping cart with packages sits on the keyboard of a laptop.

Image source: Getty Images.

The company also saw strong demand over the holiday season, a key time for retailers. It said that billions of items were ordered globally and that it sold tens of millions of Amazon devices. E-commerce trends signal more good days ahead for Amazon. According to Statista, global e-retail sales totaled $2.8 trillion in 2018 and could grow to as much as $4.8 trillion by 2021.

150 million members

There are a few significant elements that should continue to drive revenue growth at Amazon. One of them is Amazon Prime, a subscription service that offers members free next-day delivery on many items as well as other benefits such as access to movies and books -- all for an annual fee of $119. Subscription services are paying off for Amazon, contributing $5.24 billion to revenue last quarter: up 32% year over year. Amazon reported record quarterly signups for Prime and now counts more than 150 million paying members around the world.

Amazon has extended this push into the growing market of online grocery delivery. According to IBISWorld, the U.S. online grocery market expanded 16.5% annually from 2014 to 2019 to reach $33 billion. In a quest to outpace rivals, Amazon began offering free grocery delivery to Prime members in more than 2,000 communities late last year. As a result, orders more than doubled in the fourth quarter from the year-earlier period.

Alexa gets smarter

Another area where Amazon is gaining ground is with its virtual assistant, Alexa. Amazon doesn't break out revenue specifics for its devices, but it said that "hundreds of millions" of Alexa-enabled devices are now being used by customers. Amazon's continued work to make Alexa "smarter" should lead to more customers buying Alexa-equipped devices and even relying on the virtual assistant to make routine tasks easier. The company said new features include medication reminders and the ability to pay utility bills and purchase fuel. Along with everyday consumers, businesses are also putting Alexa to good use. Fiat Chrysler is adding the virtual assistant to the infotainment system for its cars, while Lamborghini will include Alexa in its Huracan Evo range.

Finally, growth may have slowed in the past year at Amazon Web Services (AWS), the company's cloud computing business, but its net revenue of $9.95 billion for the fourth quarter still came in ahead of a FactSet forecast of $9.81 billion. The business represents an important profit driver for Amazon, with AWS operating income making up 67% of the entire company's $3.9 billion in operating income for the quarter. Though investors will want to keep an eye on AWS revenue in the coming quarters, so far the slowdown hasn't been significant, and the business continues to aggressively expand its offering. Those efforts mean revenue potential in the future.

Should we buy at the high?

Amazon's diversification in technologies and businesses that somehow connect or are complementary is a strong point. If one area has a weak quarter, another area may compensate. And because the businesses are related, the company remains focused and has a better chance of delivering good results. The growth seen in Prime, grocery delivery, devices, and even AWS leaves investors plenty of reason to believe that Amazon has much farther to go in terms of revenue and earnings.

Amazon shares are trading at 91 times trailing earnings, which may seem steep, but that is actually near their lowest valuation since 2011. Though Amazon shares will surely have down days, it is difficult to see a strong reason for them to drop significantly. So, should we buy Amazon shares at the high? Sure -- because a new high is likely on the horizon.