2020 will be remembered as a volatile year in the stock market. After crashing in March, the broader market has seen high highs and low lows, and the S&P 500 index is up 10% year to date through Friday's close.

Stay-at-home stocks have scored most of the high gains so far this year, and if you had invested in Etsy (NASDAQ:ETSY), Square (NYSE:SQ), and Peloton Interactive (NASDAQ:PTON) a year ago, you would have more than doubled your money. Are further gains in store?

Exclusive products drive this e-commerce winner

Etsy's success as an online marketplace for handmade and one-of-a-kind items hasn't gone unnoticed -- certainly not by Amazon, which tried to compete with its own Handmade service. But with great management, an improved platform, and a long lead, Etsy keeps growing.

Etsy was well positioned for the pandemic, not only as a fully digital business, but with a community of makers ready to create custom masks and other pandemic paraphernalia. CEO Josh Silverman coordinated a response that spread demand among suppliers to meet increased interest in masks, resulting in millions of new customers, triple-digit sales growth for the past two quarters, and soaring earnings.

Artist with a small business.

Image source: Getty Images.

And it's far from over. Active customers are also on the increase as Etsy moves from a niche category into the mainstream and challenges the biggest names in e-commerce. The company acquired Reverb, a marketplace for musical instruments, moving into complementary businesses and adding new ways to plump the top line.

Etsy's stock has gained almost 240% over the past 12 months (based on Friday's closing price), but it fell after a great earnings report that has investors wondering about the future, and fell again on Pfizer's promising coronavirus vaccine news. While some forward progress was definitely built into its price-to-earnings ratio (P/E), its recent dip brings it down to a relatively reasonable P/E of 75, making now a great time to buy in.

Fueling new ways to pay

Square offers payment solutions for small and medium businesses as well as a peer-to-peer payments service called Cash App. But you probably already know that, since Cash App is the most popular peer-to-peer payments service in Alphabet's Google Play store.

COVID-19 wasn't kind to the company; its main business, small business payment processing, and other small business services suffered with business closures. But Cash App business, specifically bitcoin, kept revenue afloat. And now that lockdowns have for the most part been lifted, growth has resumed across the board, with a 140% sales increase and a return to positive earnings.

Small business owner with a computer in a shop.

Image source: Getty Images.

Square, with $3 billion in revenue, is nowhere near as big as rival PayPal Holdings, which has close to $5.5 billion in revenue, and PayPal's Venmo is the most popular peer-to-peer payments service in the Apple store. But Square is growing much faster, with 140% revenue growth. PayPal's maturity means its growth, while consistent, will be less eye-popping.

Square's stock has gained about 190% over the past 12 months, but investors can expect to see a lot more upside.

Pedaling toward success

Going public in September 2019, just a few months before the pandemic struck, Peloton was just in time for a stay-at-home fitness movement that lifted its sales and catapulted it into hot stock territory. 

Man syncing his watch with an exercise video on a Peloton bike.

Image source: Peloton Interactive.

In the third quarter, even after fitness-minded consumers were out and about again, Peloton showed its staying power with a 92% retention rate, 137% increase in connected fitness subscriptions, 382% increase in digital subscriptions, and 232% increase in revenue.

In fact, it's growing so fast that it can't keep up with demand, and there's a longer than one-month waiting list to purchase its premium video-connected bikes. 

Peloton has had the biggest gains of the three companies listed here, more than 280% over the past 12 months, even with a recent dip as investors cash out of stay-at-home stocks. I would say it's also the riskiest of the three, since premium bikes have a lower ceiling than payments and trinkets. But the company is making strategic moves to keep growing, such as launching new products and connecting with celebrities, and it still has years of high growth ahead.

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.