Despite years of growth in e-commerce, online retail spending still makes up less than 15% of total U.S. retail sales, according to a May 2020 report from eMarketer. With such a long tailwind of opportunity, buying leading e-commerce brands could significantly boost your investment returns.

Etsy (ETSY 3.76%), Amazon (AMZN -0.29%), and Wayfair (W 2.97%) were all doing well before the coronavirus pandemic, but these companies have kicked into another gear in this environment. These are three stocks you might be glad you bought in 20 years. Let's take a closer look at them.

A computer keyboard with icons of a shopping cart, delivery truck, globe, and credit card on the keys.

Image source: Getty Images.

1. Etsy: Capable of selling more than handmade goods

Etsy has created a unique marketplace that excels at helping small businesses and individuals sell unique or handmade items. It has delivered balanced growth in revenue and profits, which has left investors with a market-smashing return over the last five years. But the COVID-19 crisis revealed how flexible Etsy can be in expanding into new categories, which has got investors even more enthusiastic about the company's future prospects.

Etsy delivered a blistering growth rate of 137% in revenue in the second quarter. More than 100,000 sellers on the platform sold $346 million worth of face masks. That padded Etsy's top-line growth, but even non-mask sales spiked 93% year over year, with balanced growth across categories ranging from home furnishings to apparel. 

The stock has climbed 190% year to date, but it still offers long-term upside. Etsy generated just $1.1 billion in revenue over the last four quarters, but management estimates its total addressable market to be over $100 billion. As that comparison shows, this one has got plenty of growth potential to drive high returns for investors.

2. Amazon: The 800-pound gorilla

Amazon has spent billions of dollars over the years building massive fulfillment centers around the U.S. to get closer to the customer, and that paid off in a big way during the pandemic. Sales growth accelerated in the second quarter to 40%, as online grocery sales tripled year over year and Prime members shopped more often with larger basket sizes. 

That's an incredible level of growth for a business that generated $321 billion in sales over the last year. Growth may moderate as the economy reopens, but even on a trailing 12-month basis, Amazon's sales are up a robust 28%.  

Amazon also continues to dominate the cloud infrastructure services market. Amazon Web Services posted 29% growth in the last quarter and held its leading market share position steady at 33% of the market, according to Synergy Research. The high margins of the cloud business have pushed Amazon's free cash flow up to $31.8 billion over the last year. 

The stock trades at a rich valuation of 52 times free cash flow, but Amazon has always looked expensive. Investors should at least consider buying shares on the next dip. 

3. Wayfair: The leader in online home goods

Wayfair stumbled into 2020 after reporting decelerating growth to end 2019, but things have turned around in a hurry, with year-over-year revenue growth accelerating to 83% in the second quarter. 

What's more, Wayfair finally showed investors how profitable its business can be in the long run, with free cash flow coming in at $1 billion in the last quarter alone. Management is now targeting a positive adjusted operating margin going forward, assuming the business continues to grow annual revenue at 20% or better. 

Those stellar results have sent this growth stock up 271% year to date. After such a rapid rise, the stock could pull back at some point, but investors should keep their eyes on the prize. Wayfair is only generating $11.5 billion in revenue in a $600 billion home goods market. The shares might be volatile in the short term, but as with Etsy and Amazon, Wayfair has got a long way to go before it hits a ceiling.

How to get started

You don't have to go all-in with a stock. Growth stocks can sometimes be volatile, which is why it's a good idea to start small and gradually buy more shares over time. This approach allows me to not get wrapped up in short-term blips in the share price, but remain focused on what matters -- the growth of the underlying business, because that's what the stock will follow over the long term.