The Nasdaq Composite Index has tumbled more than 35% from its recent peak, putting it in a deep bear market. Given the current economic uncertainty, there's no telling how much lower it could go.

However, amid all the current challenges, many companies continue to grow their business despite the uncertainty. With their share prices tumbling, they trade at much lower valuations. Because of that, investors could score big gains by taking advantage of the sell-off and holding through the eventual recovery.

Three beaten-down companies delivering unstoppable growth are Equinix (EQIX -0.12%)Walgreens Boots Alliance (WBA -3.21%), and Zscaler (ZS 0.55%). Because of that, the 35%+ plunge in their stock prices looks like an opportunity that investors might regret missing in the future.

Remarkably consistent growth at a much more attractive price

Shares of Equinix have fallen almost 40% from their peak. One benefit of the sell-off is that the dividend yield of this data center REIT (real estate investment trust) has risen to nearly 2.5%. That's not too far off its historical high. 

That decline comes even though Equinix continues delivering unstoppable growth. The company's revenue rose another 10% in the second quarter. That marked the 78th straight quarter of revenue growth for the company, which it claims is the longest streak of any S&P 500 member. The data center REIT expects to continue growing, driven by strong demand for its data center solutions. It currently has 50 major projects underway and recently made acquisitions in Chile, Peru, and the West Africa region. These investments should help drive its continued growth. 

Given the sell-off in Equinix's stock price, investors can buy this excellent growth stock at a much lower valuation. The company sees its adjusted funds from operations (FFO) rising to a range of $28.77 to $29.10 per share this year (up 6% to 7% from 2021). With its shares recently around $510 apiece, Equinix trades at around 17.6 times FFO. That's much cheaper than the over 30 times FFO it fetched to start the year.

This dividend seems unstoppable

Walgreens Boots Alliance's stock price is down more than 35% from its recent high. That has pushed the healthcare company's dividend yield to 5.7%. That's an attractive level for a company with Walgreens' growth track record. The company has increased its quarterly dividend for 47 straight years. That easily qualifies it as a Dividend Aristocrat and has it three years away from the even more elite class of Dividend Kings

Walgreens' dividend growth streak isn't likely to stop anytime soon. The company's strategy to transform into a consumer-centric healthcare company is delivering results. Because of that, it sees its financial results accelerating in the upcoming fiscal year. Meanwhile, it has increased visibility into its long-term outlook, leading the company to expect to build to low-teens adjusted earnings-per-share growth in its 2025 fiscal year and beyond. 

With shares slumping this year, Walgreens now looks like an incredible bargain at around 7.3 times its forward price-to-earnings (PE) ratio. Not only are investors getting Walgreens for a discounted price, but they also get paid very well while they wait for the company's strategy to deliver results, thanks to its higher dividend yield. 

Blistering growth

Zscaler's stock price has tumbled more than 60% this year. Because of that, the cloud security company trades at a much more reasonable valuation of 17.7 times sales, down from over 60 times sales earlier this year. While that's still a pretty hefty price, Zscaler is rapidly growing into its valuation.

The company's annual recurring revenue surged 62% in its 2022 fiscal year, topping $1 billion for the first time. That continued its brisk growth, with Zscaler's revenue expanding at a 55% compound annual rate since 2018. Zscaler expects to continue growing rapidly, targeting to increase its annual recurring revenue to $5 billion over the next several years. That would still only give it a tiny fraction of the $72 billion market opportunity it sees for its current cloud security products. 

Zscaler utilizes a land-and-expand strategy. It wins customers to its core solutions and expands the relationship as they upgrade to new features and products. The company sees a 6x upselling opportunity within its existing customer base alone.

It's also continuing to invest in enhancing its product offerings. For example, it recently acquired ShiftRight to further improve its platform, providing additional benefits to clients. With a strong financial position, Zscaler has the flexibility to continue making investments to grow its capability so that it can continue winning, retaining, and expanding customer relationships.

Unstoppable growth at even better values

Nothing has stopped Equinix, Walgreens, and Zscaler from growing over the years. Despite their stellar growth track records, their share prices are all down sharply this year. Because of that, investors can get these unstoppable growth stocks at much lower valuations. It's an opportunity investors might regret missing in the future, since these companies should keep growing, which could eventually drive a rebound in their beaten-down stock prices.