If you're reading this article, you're probably interested in putting your money to work for you. And these days, you don't need to look further than ARK Invest CEO Cathie Wood for great investing ideas. The company's tech-focused exchange-traded funds have delivered exceptional returns over the past few years. The ARK Innovation ETF (NYSEMKT:ARKK) posted an 86% gain over the past year with annualized returns of 34% since inception. Cathie Wood has a habit of picking winners, and some of these stocks, such as Square (NYSE:SQ) and Roku (NASDAQ:ROKU), could make you rich.

The new way to manage your money

Square's been around for a while now, but it's moved way past its humble beginnings as a solutions provider for small businesses. It's expanded with Cash App, Square's personal money management app, that has grown way beyond its original purpose as a peer-to-peer payments app. It now offers stock and cryptocurrency trading, and Square recently announced a foray into online banking. In other words, Square keeps pushing the boundaries of what it can accomplish as a customer-focused fintech, or financial technology, company, and that's why it's a surefire bet for continued growth in its business and stock price.

A salesperson folding a shirt at a checkout counter featuring a Square point-of-sale device.

Image source: Square.

Cash App revenue grew 177% in the second quarter, and gross profit rose 94% year over year, powering over sales and gross profit growth of 143% and 91% respectively. Although a hefty portion of Cash App's increase came from Bitcoin trading, which the company counts as revenue, it rose 87% even without Bitcoin%. This came after a dip during the pandemic as small businesses, the bread and butter of its sellers business, closed their doors. These businesses bounced back as restrictions eased and remain a growth driver.

Doubling down on Cash App growth, Square announced that it's acquiring Australian buy now, pay later company Afterpay, adding more features for users. Rival PayPal Holdings launched its own buy now, pay later function last year, and as it prepares to launch a super app that allows users to manage their money in one place, Square is investing in its own solutions. The Afterpay deal came on the heels of the Square Banking announcement, to round out Square's own bid to offer a one-stop money management shop.

Square stock gained more than 2,000% over the past five years, and if you were too late to get those returns, you can start now.

Four people sitting on a couch.

Image source: Getty Images.

The new way to watch

Roku was one of the biggest winners during the pandemic as customers turned to its devices and streaming networks for home entertainment. Investors had a field day with Roku stock as sales soared, and the stock gained almost 200% in 2020. But it hasn't maintained that performance in 2021 as the company laps high growth from last year and deals with supply issues. That's great for forward-thinking investors, who can buy before the stock explodes again. 

Roku's third-quarter guidance isn't too exciting at about 50% year-over-year sales growth, but that's on top of last year's super growth. People are going out again after months at home, which is affecting the company in the short term. That's why streaming hours decreased from the first quarter (although they increased year over year). But after consumers get their fill of the outside world, the two will balance out, and Roku should begin to see higher growth in sales and viewing hours. One hint that this could happen is that although streaming hours were down from the first quarter, they were not only 19% higher year over year, but that was its highest increase over the past five quarters.

A new potential threat to Roku's operating system dominance is Amazon's recent announcement that it's rolling out an aggressively priced line of streaming devices under the Fire TV brand. But although investors didn't react kindly to that announcement, it's a good sign that the market is still growing, despite Roku's unimpressive year-over-year growth rates for its player business (sales were about flat in the second quarter). Roku has the No. 1 spot in the U.S. streaming device market, and Amazon's new entry doesn't present a serious threat to that dominance.

In the meantime, Roku's platform business is still demonstrating strong growth, with a 117% increase year over year in Q2, and that's where its greatest opportunities lie right now. This hasn't slowed down, and as Roku invests in its free Roku Channel with its own content and strikes more deals with third-party networks, expect to see sustainability and increased sales.

Roku stock is slightly down year to date, making now an ideal time to jump in.

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.