2020 has been a landmark year for stocks trading on the Nasdaq Stock Market. The Nasdaq Composite (NASDAQINDEX:^IXIC) has dramatically outpaced the gains of other major market benchmarks, showing the strength of the companies that call the Nasdaq home.

As we head into 2021, the Nasdaq is fertile ground for rising stars in the stock market world. The entity in charge of overseeing which companies make up the prestigious Nasdaq-100 Index recently announced that six brand-new members would join the index effective Monday, Dec. 21.

One of them, American Electric Power (NYSE:AEP), got the nod solely because it moved from the New York Stock Exchange (NYSE) to the Nasdaq earlier this year. However, the other five have posted huge gains in 2020 and look poised to continue their winning ways in 2021. Let's take a quick look at all five to see which have the most promise.

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1. Peloton Interactive

Peloton Interactive (NASDAQ:PTON) has been the high-flyer of this group, with shares nearly quintupling in 2020. The at-home interactive exercise-equipment maker has resonated with fitness fans for a while, but the COVID-19 pandemic really boosted demand for its stationary bikes and treadmills. Now, the company is in the enviable position of having more interested customers than it can keep up with from a supply-chain standpoint.

Person holding weight next to treadmill with display showing a video.

Image source: Peloton Interactive.

Some fear that recent moves from competitors as large as Apple to duplicate its line of interactive fitness content could catch up with Peloton's breakaway. However, Peloton knows the first-mover advantage it has, and it's doing everything it can to maximize the value of its platform for subscribers -- both those who currently own Peloton equipment and those solely using its app. That bodes well for Peloton's staying power even after the pandemic is under control.

2. Okta

Shares of Okta (NASDAQ:OKTA) are up 133% so far in 2020, and it's easy to see why. When your entire workforce has to move to the cloud because of restrictions on gathering at nonessential places of employment, you need the identity-verification software platform that Okta provides to ensure that your vital proprietary information remains secure.

That increased demand has shown up in revenue growth, with Okta's sales climbing 42% year over year in the third quarter. The biggest news from Okta is that big financial institutions are finally starting to get interested in the company's services. With banks typically being the last to sign on with new technology, that milestone is an important one for Okta and will provide another leg up for revenue in 2021 and beyond.

3. Atlassian

Australia's Atlassian (NASDAQ:TEAM) has climbed onto the workplace-collaboration bandwagon, with numerous platform tools designed to help people work more effectively together. For instance, its Trello productivity software helps manage workflows from anywhere, streamlining production and ensuring on-time delivery and completion of projects.

The rising need for help in collaborating remotely has been a big factor in Atlassian's stock doubling in 2020. Yet the company is still building up its product portfolio to include even more tools and has ambitious plans for greater international penetration in markets it hasn't yet tapped. With efforts like its in-house venture fund to help bolster new apps, Atlassian hopes to keep bringing in new subscribers and keep its growth at top speed.

4. Match Group

Match Group (NASDAQ:MTCH) is the company behind the popular mobile-dating app Tinder, among other online dating services. With offline dating methods largely put on hold during 2020 due to the pandemic, Match's properties have done extremely well. The company has global scope, and recently, its international business has done even better than its domestic operations.

Long-term trends favor online dating, so Match has an opportunity to keep growing well beyond 2021. Despite a more than 90% rise for the stock, Match Group has room to run higher in the coming year.

5. Marvell Technology

Finally, Marvell Technology (NASDAQ:MRVL) has been taking advantage of the upgrade cycle for new 5G wireless network technology. Marvell's semiconductors are designed to help its customers keep up with advances in technology in areas ranging from cloud computing to automotive and wireless solutions, and with the rollout of 5G, Marvell's products have been in high demand. That's sent the stock up more than 80%.

The 5G revolution is only just beginning, however, with the rollout of smartphones and mobile devices that use the full capabilities of upgraded wireless networks. With wireless carriers rushing to get 5G functionality out to as many customers as possible, Marvell should continue to see big purchases far into the future.

Keep your eyes on these winners in 2021

Some investors would warn that the stocks that have done the best in 2020 will necessarily have to give up ground in the coming year. But for strong businesses with a lot of potential, upsurges can last a lot longer than you'd think. Regardless, these five companies will get a lot more attention as part of the Nasdaq-100 Index, and that makes them worth watching in 2021.

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.