2017 was a wild year for online retail technology provider Shopify (NYSE:SHOP). The company has been growing at breakneck speed, but took some verbal abuse from short-selling firm Citron Research in early October. Since then, the stock has been moving sideways, unable to regain upward momentum. That could soon change, though, making Shopify worth another look.

SHOP Chart

Data by YCharts.

Is revenue the end-all, be-all?

Shopify's explosive growth has been touted as a main reason for owning the stock. And why not? The company has reached annualized sales of over $600 million when extrapolating results from its third quarter of 2017 (full-year figures should be released in February) and is still growing north of 70% year over year. Should that pace continue, that would edge Shopify over $1 billion in annual revenue as soon as this year.

A chart showing revenues grew 95% in 2015, 90% in 2016, and 74% through the first three quarters of 2017.

2017 year-to-date = through the first three quarters of 2017. Chart by author. Data source: Shopify.

However, Citron's scathing criticism last year raised issues about the sustainability of revenue growth, sparking questions about Shopify's recruiting methods and levels of "churn." Churn refers to subscribers discontinuing use of a service.

Shopify has long been a promoter of small business and entrepreneurs, focusing on helping small retailers and manufacturers of product sell their wares online. The company charges customers a monthly fee, so the more sites using its products, the more money it makes. Citron's beef with management therefore has some merit, as Shopify doesn't discuss its churn rate -- the percentage of online stores and entrepreneurs leaving its service.

Three young women walking down a street holding shopping bags.

Image source: Getty Images.

And revenue growth is slowing down. Perhaps part of that is due to churn, but Shopify doesn't just make money by signing up new customers. The more money its merchants are making, the more money Shopify makes. The company calls this segment of its business "merchant solutions." It grew by 79% in the last reported quarter, and now makes up 52% of total sales. The segment is still growing, too, with Shopify reporting its merchants sold more than $1 billion of merchandise over the Black Friday shopping weekend for the first time.

If not sales, what else?

There's another reason to think Shopify's run could continue: an improving bottom line. As is the case with many fast-growing businesses, Shopify is not yet profitable, but that may be changing.

Gross revenue has been steadily rising, almost doubling every year since 2015. Operating loss jumped in 2016, but has been slowly edging back towards breakeven.

2017 year-to-date = through the first three quarters of 2017. Chart by author. Data source: Shopify.

Shopify's costs to operate grew after becoming a public company in 2015 as the company worked to spur growth. However, in the last year, gross profits have been growing faster than expenses, and Shopify's operating loss is beginning to shrink. Both are good signs that the company is on a path to profitability.

During the last reported quarter, the company reported its first-ever profit when backing out stock-based compensation expenses. That's not a replacement for actual profitability, but it is another good sign the company is making progress. 

Ignoring the numbers

Both the top- and bottom-line numbers show a business that is still on a strong growth trajectory, albeit with some healthy debate over sustainability. However, the real reason to own the stock is the massive shift in the way consumers spend money. Online shopping is still barely over 10% of total retail in the U.S., but that figure is growing by double digits.

Shopify is the leader in helping entrepreneurs and small retailers capitalize on that online trend, and the company has a number of big names in its camp as well. I'll admit that Shopify isn't the type of business I typically buy for my portfolio (I prefer better-established and already profitable companies). Financial figures aside, though, the internet megatrend that the company is benefiting from is enough to make me think this one is worth buying in 2018.

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.