Investors have been getting whiplash from the stock market in recent weeks. After descending into the fastest bear market in history, the major indexes have come roaring back, but significant volatility remains. Yet even as the market careens forward, there are plenty of opportunities for investors to benefit.

More importantly, you don't have to have a lot of money to invest to be successful. The major brokerage houses have largely done away with commissions and many even permit the purchase of partial shares, making the stock market an appropriate venue for investors in any tax bracket.

If you have just $500 (or less) in disposable cash right now that you don't need to pay bills or augment your emergency fund, buying shares in these companies that have enormous growth prospects would be a genius move.

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Twilio

The ability to communicate with customers from within apps is becoming increasingly important, for everything from password resets to rideshare alerts and everything in between. That's why Twilio (NYSE:TWLO) was such a game changer. The company provides the building blocks that made it a snap for app developers to incorporate Twilio's technology into their own messaging systems, accomplishing in hours what previously took weeks.

It doesn't stop there. The company hosts 25 cloud data centers in nine geographic regions that serve developers in 180 countries around the world. Twilio's growing list of customers, which numbered more than 179,000 at last count, continues to expand beyond its North American roots, with 29% of its revenue from international markets in 2019, up from 23% in 2017. 

Revenue grew by 75% year over year in 2019, while Twilio's dollar-based net expansion rate of 136% shows that once customers are on board, they not only stick around, but tend to increase their spending over time. That's why management is forecasting full-year 2020 revenue growth of about 30%. 

Fortunately, Twilio has sufficient reserves to make it through tough times, with $1.8 billion in cash and just $458 million in debt. It's worth noting, however, that the debt is convertible to equity, so it represents less of a financial risk.

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Arista Networks

While cloud computing is already big business, it will only get bigger from here. That said, it's increasingly difficult to know how to profit from the cloud market, as growth is slowing among the biggest players. That's where Arista Networks (NYSE:ANET) comes in.

The cloud specialist doesn't provide any of the software-as-a-service (SaaS) or infrastructure-as-a-service (IaaS) platforms offered by the larger players, but rather provides the routers, switches, and software that connect servers and other equipment to cloud data centers.

Arista has more than 6,300 customers in 94 countries, but data center giants Microsoft and Facebook accounted for 23% and 17% of total revenue last year, respectively, and that's part of the reason the stock is selling at a bargain basement price. 

One of these large customers (it's widely believed to be Facebook) temporarily scaled back its cloud build-out last year, causing Arista's stock to lose over a third of its value over the past 12 months. As a result of the lower cloud spending, revenue increased by just 12% year over year in 2019. That spending is merely delayed, not gone, and when it resumes, Arista stands ready. Fortunately, the company has a rock-solid balance sheet, with $2.7 billion in cash and no debt, that will help it ride out temporary business hiccups like these. 

If you believe as I do that the need for data centers is only going to grow from here, and that the speedy movement of data will be paramount to future success, then adding Arista right now would be a smart move, before spending ramps back up.

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Amazon

It would be hard to find a company that has benefited more from sheltering at home than Amazon.com (NASDAQ:AMZN). Its e-commerce services have become an indispensable part of living and working from home.

Orders have been off the charts, with Amazon rushing to hire as many as 175,000 workers to augment its delivery and fulfillment center staff. Amazon was even forced to wait-list its grocery delivery service -- Amazon Fresh -- because it couldn't keep up with the unprecedented demand. The company then took the extraordinary step of suspending storage of non-essential items in its warehouses to make much-needed room for consumer staples and medical supplies.

Yet it isn't just the digital shopping business that's thriving amid the stay-at-home orders that still blanket most of the U.S. A number of businesses have taken to working remotely, and many can do that thanks to Amazon Web Services (AWS), the company's cloud computing service. AWS is the clear leader in the space and is among Amazon's most profitable businesses, boasting 26% operating margins, while also generating plenty of cash the company can invest in other areas of its business.

Consumers are turning to Twitch -- the company's livestreaming videogame service -- and Amazon Prime Video for their in-home entertainment needs.

Amazon's revenue was up 21% year over year in the fourth quarter -- an impressive achievement for a company with a $1 trillion market cap -- while profits grew 6%, even as Amazon invested heavily in its one-day shipping initiative. Those aspirations went by the wayside during the pandemic, likely strengthening the company's bottom line in the process.

The e-commerce giant also has a massive war chest, with more than $55 billion in cash and marketable securities on its balance sheet, and just $23 billion in long-term debt, with more cash being generated every day.