Tech stocks have taken a bit of a beating recently as the Nasdaq has fallen faster than the broader market. This tech-heavy index is only down single digits from its high, but it could go lower. Savvy investors often have a "ready-to-buy" list if the market crashes. We asked three Fool contributors what stock they would buy without hesitation if the market decides to pull back even more in October. They came up with The Trade Desk (TTD 3.35%), StoneCo (STNE 0.32%), and Cloudflare (NET -0.23%).

Couple on couch browsing online.

Image Source: Getty Images.

The Trade Desk: Seeing the bigger picture

Danny Vena (The Trade Desk): Advertising is in the midst of a once-in-a-generation paradigm shift. Viewers no longer rely on programming schedules for appointment-type viewing. The shotgun approach -- or one-size-fits-all -- style of advertising is going the way of the dinosaur. Target markets are as scattered as they are difficult to reach. That's where The Trade Desk comes in.

The company's cutting edge platform isn't bound by traditional constraints and has the ability to assess 12 million ad impressions and quadrillions of permutations every second. This not only gives marketers more bang for their buck but also helps them better reach a fragmented target market.

One sign of the value of The Trade Desk's platform is the company it keeps. Rather than competing with the world's largest advertising agencies, it partners with them using the data it gathers to further strengthen its algorithms. The company uses state-of-the-art technology to make split-second decisions with lightning precision.

A recent announcement by Alphabet's Google that it will do away with ad-tracking cookies caught some investors off guard, leading to concerns that The Trade Desk's advertising business could suffer. CEO Jeff Green spoke frankly about the issue earlier this year, pointing out that this move has been anticipated for several years. 

The Trade Desk isn't concerned about the death of cookies for several reasons. First, the company has constructed Unified ID 2.0, the most widely accepted alternative to cookies in the ad industry. The platform has been adopted by a long and growing list of top tier names in advertising, giving The Trade Desk a notable edge.

Additionally, cookies only matter when tracking users across the internet, which only amounts to roughly 20% of data-driven ads. This ignores the biggest growth areas in digital advertising, namely streaming audio, video, mobile, in-app, and connected TV. These are also, not coincidentally, the areas where The Trade Desk really shines, with growth far outstripping traditional advertising venues, including broadcast and pay TV.  

The Trade Desk's recent results paint a compelling picture. Revenue in the second quarter grew 101% year over year, though that was partially the result of easy comps. At the same time, earnings per share also doubled, and customer retention stayed above 95%, which it has done every quarter stretching back seven years. 

Finally, when looking for a stock to buy during a stock market crash, historical perspectives matter. In February of last year -- as panic regarding ad spending set in -- The Trade Desk stock was among those hardest hit, falling roughly 54%. However, after hitting bottom in late March, The Trade Desk rocketed higher, climbing more than sixfold from its lows and more than triple its previous all-time high, which it hit just prior to the start of the pandemic. 

This shows that The Trade Desk is as resilient as it is successful. That's why investors shouldn't hesitate to buy the stock if there's a stock market crash in October.

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Image source: Getty images.

StoneCo: User growth continues amid headwinds

Will Healy (StoneCo): If American investors have heard of StoneCo at all, they may know the Brazilian fintech stock as a company Warren Buffett's team at Berkshire Hathaway bought before its 2018 initial public offering (IPO).

Still, amid competition from e-commerce giant MercadoLibre, PagSeguro Digital, and now Sea Limited, StoneCo has earned business by eliminating "bureaucracy." It goes to the client, finding areas of demand, and then quickly opens sales offices near its customers. This personal touch probably contributed to its rapid revenue and stock growth in past years.

However, COVID-19 hit Brazil particularly hard, dramatically slowing the company's growth. Also, challenges with a new credit registry system forced the company to freeze new loans temporarily, which CEO Thiago Piau said "contributed negatively" to reported revenues.

Consequently, in the first half of 2021, revenue of just under 1.5 billion Brazilian reais ($270 million) rose just 7% compared with the first six months of 2020. This is a considerable decline from the 63% revenue growth reported for a 12-month period in 2019 right before the pandemic started. Also, the company would have reported a loss in the first two quarters of 2021 if not for an R$841 million ($153 million) unrealized gain on an investment in Banco Inter, a Brazilian digital bank.

Admittedly, an October crash would increase StoneCo's appeal. Nonetheless, since this stock has fallen by about 65% since February, investors need not wait for a market crash to buy this growth stock.

The decline has taken its price-to-sales (P/S) ratio down to 17, far from its sales multiple of about 45 when the stock price peaked in February. Moreover, that is barely higher than PagSeguro's P/S ratio of 14, a stock that has traded at a significantly lower valuation than StoneCo for most of the last two years.

Also, StoneCo continues to show signs of robust expansion. In the first half of 2021, the total payment volume (TPV) of R$111 billion ($20 billion) surged by 47% versus the first six months of 2020. Furthermore, active payment clients of almost 767,000 grew by 45% over the same period. Such metrics indicate that once StoneCo can get past the pandemic and the credit system challenges, massive growth in both the company and the stock should resume.

Two individuals are checking on the cloud servers in a data center.

Image source: Getty images.

Cloudflare: This high-flying growth stock makes cloud computing easier

Brian Withers (NET): Cloudflare stock has been on a tear this year, up over 75%. While its fundamentals have improved, there's lots of excitement priced into this stock. Its price-to-sales (P/S) ratio is reaching a high-altitude, cirrus-cloud level of 77. But if the market pulls back in October, this is one you'll want to add to your portfolio. Let's find out why.

First, the recent top-line growth and customer numbers are top-notch.


Q2 2020

Q1 2021 

Q2 2021

QoQ change

YoY change


$100 million

$138 million

$152 million



>$100K ARR customers 






Dollar-based net retention






Source: Company supplemental financial information document.

Second, the company is growing its addressable market by adding adjacent products. When the company went public, it targeted its addressable market at $32 billion focused on its Cloudflare Application Services. By 2024, it expects its market to be $100 billion with general category growth and the addition of its Cloudflare Network Services and Cloudflare Zero Trust Services. With this rounding out of its offerings, it is making a more attractive platform for customers to grow their spend over time. Its most recent quarters' record 124% dollar-based net retention is evidence this strategy is working.

Lastly, the market for cloud computing is becoming a massive market. International Data Corporation (IDC) forecasts the market for cloud computing and all of the related hardware, software, and professional services to be $1.3 trillion by 2025. This is up from $707 billion in 2021, representing a compound annual growth rate of 17%.

This easy-to-onboard cloud service is attracting more customers and growing its market. If the only thing holding you back is its lofty valuation, this would be a great stock to add to your watch list in case the market pulls back this month.