Many investors choose to avoid risky stocks. And in some cases, that's a great idea. There are plenty of low-risk stocks that offer excellent returns. But if you're an aggressive investor, it's also a great idea to consider a few stocks that are early in their story -- but may have some extremely exciting chapters ahead.

Right now, I'm thinking of a biotech company with game-changing vaccine technology and a company whose successes are tied to the cryptocurrency market. Both stocks have dropped about 25% so far this year. And both are trading below Wall Street's lowest average 12-month share price forecasts. These players are risky -- but long-term potential is enormous.

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1. Vaxart

The coronavirus pandemic put Vaxart's (VXRT -4.29%) name on the map. That's because this biotech company jumped into the vaccine race early on. The company's program hasn't yet reached the finish line though. Vaxart's candidate still is in phase 2 trials. The company aims to report data from the study in the first quarter of this year.

Of course, Vaxart's candidate -- if successful -- will arrive late. Rivals already have vaccinated a big part of the population. But that might not matter. Here's why. Vaxart's potential product is an oral vaccine. It's a tablet to be taken with a glass of water. This could make Vaxart popular with patients and healthcare providers. Many patients would love the idea of a vaccine without a needle stick. And providers will appreciate the ease of transporting and storing a pill versus a traditional vaccine that requires cool temperatures. So, Vaxart may carve out market share as people return for boosters. And such doses may be needed over the long term. Experts say the coronavirus will stick around. That means people will continue to need vaccines as protection.

Vaxart also is working on oral vaccine candidates for seasonal flu, respiratory syncytial virus, and human papillomavirus. The seasonal flu candidate is in phase 2 studies. So, between the coronavirus and the flu candidates, Vaxart may have the opportunity to bring a product to market in the next few years.

Vaxart is risky because it hasn't yet brought an oral vaccine to market. And failure can happen at any point during clinical trials -- even in late-stage studies. This situation is the same for all clinical stage biotech companies. But in the case of Vaxart, if it succeeds and commercializes oral vaccines, we could be talking about blockbuster future revenue -- and major share gains.

2. Coinbase

Coinbase Global (COIN 3.09%) is a cryptocurrency exchange. And most of its revenue comes from transactions. For example, the company reported $1.1 billion in transaction revenue in the third quarter of last year. That's on total revenue of $1.2 billion.

So Coinbase is extremely dependent on activity in the cryptocurrency market. This represents both an enormous opportunity for Coinbase and its investors -- as well as a good deal of risk. In a booming crypto market, Coinbase's revenue could skyrocket. We've seen this happen already. For example, the crypto market's strength in the second quarter of last year resulted in Coinbase generating $1.9 billion in transaction revenue. But if the trading of cryptocurrency declines, so will Coinbase's revenue.

Right now, the cryptocurrency market is young. Thousands of crypto players aim to transform the way business is done. Some of them also are changing the way art is collected -- through non-fungible tokens -- or the way games are played -- think metaverse. It's still too early to say whether some or all of these efforts will be successful. If users and investors lose interest in cryptocurrencies, Coinbase's revenue could plummet. An investment in Coinbase is a bet on the success of cryptocurrencies. If more and more investors flock to cryptocurrencies, Coinbase trading revenue will soar -- and Coinbase and its investors could win big.