2020 was a record year for initial public offerings (IPOs), with 480 companies going public on U.S. stock exchanges, and more stocks doubling in their first day of trading than ever before. 2021 is on track to be another huge year for IPOs, and some innovative companies making public market debuts could go on to deliver tremendous returns. 

With that in mind, we asked three Motley Fool contributors to profile a recent or upcoming IPO stock that looks primed to be a big winner. Read on to see why they identified PubMatic (NASDAQ:PUBM), Instacart, and Coinbase as IPO stocks that are poised for explosive performance this year. 

Blocks spelling out 'IPO.'

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A small-cap bet on a big digital advertising trend

Keith Noonan (PubMatic): Digital advertising is at the heart of the internet experience. Nearly every media site and social media platform that doesn't exclusively rely on subscriptions is built around advertising, and tech giants including Alphabet and Facebook have built massive tech empires on the foundation of strong digital ad units.

The digital advertising revolution is still at a relatively early stage, and PubMatic is a promising player that could wind up delivering huge returns for patient shareholders. The programmatic advertising specialist had its initial public offering on Dec. 8, and its share price has climbed roughly 25% since market close on the day of its debut. The stock still offers explosive upside.

Data analytics and artificial intelligence technologies are revamping the way advertising campaigns are targeted and deployed, giving companies the opportunity to track real-time data results and pivot targeting on a dime. Internet media and commerce revolves around grabbing and holding attention, and PubMatic provides a cloud software platform that makes it easy to connect ad buyers and publishers and track up-to-date info on whether campaigns are effective.

Big names including Forbes, Microsoft, and Unity Software already rely on PubMatic's solutions, and the advertising specialist has big room for growth as it brings new customers on board its platform and delivers results that encourage increased spending per client. With a market capitalization of roughly $1.8 billion, PubMatic is still in small-cap territory and even smaller wins amid a backdrop of momentum for its industry niche could translate to big stock gains. 

Grocery delivery is the next frontier of e-commerce

Jamal Carnette (Instacart): Talk about a delivery markup: Last year soon after taking a private round of funding at a $17.7 billion valuation, on-demand grocery delivery company Instacart shocked investors by announcing it had entered a deal with Goldman Sachs to go public early in 2021 at an estimated value of $30 billion. In the long run, the company will likely be worth significantly more than that figure.

Instacart benefited from the pandemic, as the service was able to take online grocery market share away from Walmart during the lockdown. However, it's folly to believe the bearish argument there will be mass exodus when we return to normal as this doesn't account for human behavior. Much like e-commerce, once users discover the convenience of online grocery delivery, they tend to continue or at least adopt a hybrid shopping model.

The online grocery market is quickly resembling the e-commerce market of 10 years ago and battle lines are being drawn now. Amazon is moving forcefully to build out distribution centers and Amazon Fresh stores that double as critical last-mile delivery centers. Target and Walmart spent big to beef up their e-commerce operations: Walmart acquired Jet for $3 billion in 2016 and Target acquired Shipt for $550 million in 2017.

If the remaining grocers are looking to compete against behemoths in this space quickly, cheaply, and at scale, there's no better solution than Instacart. Keep an eye on this IPO.

The cryptocurrency titan

Joe Tenebruso (Coinbase): Bitcoin is once again making headlines after its price soared to new all-time highs above $40,000. If you'd like to profit from bitcoin's popularity -- without the risks of investing directly in cryptocurrency -- buying Coinbase's stock could be a great way to do so.

The leading U.S. cryptocurrency exchange is prepping for its stock market debut. Coinbase's initial public offering will reportedly take place as early as February, in what's widely expected to be one of the biggest IPOs of the year.

Coinbase is no doubt benefiting from the rising interest in bitcoin and other digital assets among investors. Trading volumes tend to increase along with prices, which, in turn, boost profits for exchanges.

With bitcoin becoming a more accepted investment among hedge funds and family offices now that respected investors -- such as Paul Tudor Jones and Stanley Druckenmiller -- have added the cryptocurrency to their widely followed portfolios, trading volumes are likely to rise even further in the coming months. Coinbase's revenue and earnings could thus be poised to soar. All of this bodes well for Coinbase's upcoming IPO, which is likely to be well received by professional and individual investors alike.

Early valuation estimates for Coinbase vary widely. Crypto market analysis company Messari valued the exchange at $28 billion in December, while recent reports have Coinbase's market value reaching as high as $75 billion. Coinbase's final IPO price will be determined after more investors have had the opportunity to peruse its as-yet-undisclosed financials. But based on what we do know, if Coinbase's IPO settles at the lower end of that price range, its stock could be an attractive buy for long-term investors.

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.