There's little doubt that the digital signature market got a big boost from the pandemic, and as the industry leader, DocuSign (NASDAQ:DOCU) was a major beneficiary. During the first nine months of 2020, revenue grew 46% year over year, while the company's operating loss edged lower. While DocuSign's dominance of the e-signature space still represents a significant market opportunity, there's another one that's just as big waiting in the wings.

On this clip from Motley Fool Live, recorded on Feb. 18, "The Wrap" host Jason Hall and Fool.com contributor Danny Vena discuss a fledgling business that effectively doubles DocuSign's total addressable market (TAM) and why investors shouldn't sleep on its massive potential.

Jason Hall: Each of us. Danny, I'm going to ask you to start here. What is a high-growth stock you think is worth buying right now?

Danny Vena: A lot of times I'll look at stocks and one of the things that I see is that an investment opportunity will be created because there's a disconnect between what investors believe a company does, and what it actually does. I will give you an example. Roku (NASDAQ:ROKU) is pretty classic. For a long time, many investors just associated Roku with the streaming dongles and devices that it pioneered, and dismissed the company outright as lacking in opportunity, not realizing that Roku made the majority of its money from digital advertising. So that's an example.

Right now, I think investors are making a similar mistake with DocuSign. DocuSign is the industry leader in the digital or e-signature space, and they have an estimated 70% of the market. As we know because of the pandemic, adoption of digitally signed and approved documents has accelerated, and that's leaving many investors wondering if the train has really left the station and is there any further upside for DocuSign?

Now management has been very quick to point out that digital signing of documents is really just the start of a relationship with its customers. So what happens from there is that once they get used to the utility of the digital signature, many of those customers move on and become customers of DocuSign's agreement cloud.

The agreement cloud is something that DocuSign introduced in early 2019, marking the next step in the company's evolution. This platform is a suite of about a dozen applications, and more than 350 integrations that help companies manage the entire life-cycle of contracts and agreements.

What it does is it helps companies prepare, sign, act on, and manage the documents. One of the customer testimonials on its website said that "On average, we've been able to close deals in less than half a day compared to five days" when they don't use the agreement cloud. So this is a big time saver.

Over the last year, DocuSign has grown quickly. In Q3, revenue grew 53% year over year, subscriptions grew 54%, and billings, which includes sales that have been contracted for but are not yet included in the revenue jumped by 63%. The company's not yet profitable, but it's free cash flow moved into the plus column after the company was burning cash in the year-ago quarter.

So I think this is a massive opportunity here. DocuSign says that its e-signature market is about $25 billion opportunity, and the agreement cloud doubles that. This is a company that generated revenue of less than $1 billion in 2019. So when you look at the $50 billion total addressable market, I think this is a stock that investors are sleeping on, and really need to add to their portfolio before the rest of the investors catch on.

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.