Back in 2016, Bank of America/Merrill Lynch released a report that examined the performance of value stocks and growth stocks over a 90-year period between 1926 and 2016. Interestingly, value stocks have outperformed over the long run, with an average annual return of 17%, compared to 12.6% for growth stocks.

But what really stood out from the B of A/Merrill Lynch study is how these roles have reversed since the Great Recession. For about a decade, growth stocks have run circles around value stocks, with historically low lending rates to thank for this outperformance. Since growth stocks tend to lean on debt-based financing for expansion, and this financing can be had for an historically low cost (i.e., less interest expensing), it's really ramped up the sales growth potential for certain stocks and industries.

With historically low lending rates expected to persist for some time, here's a look at three unique growth stocks that only seem to be getting better with age.

An Amazon fulfillment employee getting items ready for shipping.

Image source: Amazon.

Amazon

Just as Apple has seemingly been the no-brainer investment of the past decade, Amazon.com (AMZN 1.16%) looks to be the no-brainer growth opportunity you won't want to miss over the next decade. And yes, this takes into account that the company is already worth almost $1 trillion.

When most folks think of Amazon, they rightly think of its dominant retail platform. There's certainly nothing wrong with this impression of Amazon as it's a big reason the company has been able to generate significant sales and build up an incredible following through its Prime membership. In the first quarter of 2019, $52 billion out of $59.7 billion in net sales was essentially derived from retail sales, either through its Amazon platform, its wholly owned grocery chain Whole Foods, or other means.

But what's particularly interesting about Amazon is that it's the company's cloud services for small-and-medium-sized businesses, Amazon Web Services (AWS), that's really the key to its future growth. Not to belittle the importance of Amazon's monstrous e-commerce market share, or the loyalty that its Prime membership brings, but none of its retail operations can hold a candle to the margins AWS brings to the table.

Out of the aforementioned $52 billion in net sales from retail, Amazon logged operating income of $2.2 billion in the first quarter. But from just $7.7 billion in AWS sales, Amazon also logged $2.2 billion in operating income. With AWS growing at a much faster pace than its traditional e-commerce business, AWS will continue to represent a larger percentage of sales over time, thereby improving margins, cash flow, and profitability. Not surprisingly, Wall Street has forecast a near-tripling in cash flow per share for Amazon between 2018 ($61.45 per share) and 2022 ($178.40 per share). 

In other words, AWS makes Amazon a much more reasonably valued stock than you probably realize.

A surgeon holding a one dollar bill with surgical forceps.

Image source: Getty Images.

Intuitive Surgical

When it comes to surgically assisted robotic medical-device developers, there's Intuitive Surgical (ISRG 0.19%) and everyone else – and that might be giving Intuitive's competition too much credit.

As of the end of March, it had 5,114 of its da Vinci surgical systems installed in hospitals and universities around the world. That's an incredible figure given the understanding that it's been installing these systems for less than two decades. 

Most people probably think that Intuitive Surgical's business model is dependent on it selling plenty of its high-priced surgical systems. Since the da Vinci systems can cost between $500,000 and $2.5 million, it certainly does generate quite a bit of revenue for Intuitive Surgical. But these machines are also cost-intensive to build, meaning they're generally a low-margin sales component for the company.

What allows Intuitive Surgical to get better with age are its two other sources of recurring revenue: procedural instruments and system servicing. Every time a new procedure is performed using the da Vinci system, new instruments are used. In true razor-and-blade fashion, Intuitive expects to reap significant rewards as its installed base of da Vinci systems increases and instrument sales grow as a percentage of total revenue.

Further, Intuitive Surgical services its da Vinci surgical system, which is another high margin source of sales. Both servicing and instruments are becoming a larger source of total sales, which is a boon to the company's long-term margins and profitability, even if its top-line sales growth slows a bit.

A driver pressing a button on their Sirius XM in-car interface.

Image source: Sirius XM Holdings.

Sirius XM Holdings

Growth stock investors would also be discouraged from turning the dial away from Sirius XM Holdings (SIRI), despite some minor recent hiccups following its acquisition of music-streaming service Pandora.

When most investors think about the radio, they probably envision a stodgy business model that's highly dependent on advertising – and they'd be right. While the terrestrial and online radio model can do exceptionally well during periods of economic expansion, their reliance to advertising proved to be a fatal flaw for some operators during the Great Recession.

What makes Sirius XM so unique is that its business model largely de-emphasizes ad revenue. Prior to the acquisition of Pandora, the bulk of Sirius XM's revenue was from subscriptions, with advertising comprising around 3% of total sales. Even after adding Pandora into the fold – a majority of Pandora's revenue is from ads – Sirius XM is only generating 12% of total sales from ads, as of the first quarter. This desensitizes the company from economic hiccups and recessions, which is not the case with its terrestrial and online peers. 

More importantly, Sirius XM is the only game in town when it comes to satellite radio. No matter how many subscribers the company continues to add to its network, transmission costs for its satellites will remain relatively fixed. With the exception of talent acquisition costs and royalties, which can vary from quarter to quarter, this suggests some level of predictability that Sirius XM's margins will rise over time as its subscriber base expands.

In sum, expect Sirius XM to age very well in growth stock investors' portfolios.