The stock market is a happy hunting ground for investors so far this year, with the S&P 500 up 24.7% from bear market lows hit last October, driven mainly by technology stocks that have benefited from the artificial intelligence (AI) craze in 2023.

The S&P 500 is up 13% so far this year, the tech-laden Nasdaq-100 Technology Sector index has soared 36% over the same timeframe. The broader stock market's gains have also lifted the likes of CrowdStrike (CRWD -1.80%) and Zscaler (ZS -1.03%), two fast-growing companies that are set to capitalize on massive end-market opportunities.

While CrowdStrike stock has soared 36.5% so far this year, Zscaler is up 27.6%. Let's look at the reasons why these high-flying stocks are likely to sustain their upward momentum in 2023 and beyond.

1. CrowdStrike Holdings

CrowdStrike Holdings is known for its cloud-based cybersecurity solutions, a fast-growing niche that has allowed the company to deliver outstanding growth in recent years.

CRWD Revenue (TTM) Chart

CRWD Revenue (TTM) data by YCharts

The size of the cloud security market is set to expand rapidly in the long run. According to a third-party estimate, the cloud security market was worth $20.5 billion last year. By 2032, it is expected to generate close to $150 billion in annual revenue, clocking an annual growth rate of 22.5% over the next decade.

CrowdStrike's estimates, however, are far more ambitious. The company sees its total addressable market (TAM) jumping from $76 billion in 2023 to $98 billion in 2026. But that estimate is based on the current portfolio of CrowdStrike's offerings. The cybersecurity specialist sees its potential TAM jumping to $158 billion in 2026 after accounting for its future product roadmap and initiatives.

Given that CrowdStrike generated $2.45 billion in revenue over the trailing 12 months, it is easy to see that there is massive room for growth going forward. Not surprisingly, CrowdStrike has been making the most of the lucrative cloud security opportunity by building a robust customer base that's paving the way for long-term growth.

This is evident from the fact that CrowdStrike's annual recurring revenue (ARR) increased 42% year over year in the first quarter of fiscal 2024 (for the three months ended April 30, 2023) to $2.73 billion. The company calculates ARR as the annualized value of customer subscription contracts at the end of a particular period, so the rapid increase in this metric bodes well for CrowdStrike's future.

This impressive jump in CrowdStrike's ARR is not surprising, as the company's customers are adopting more of its solutions. For example, 62% of the company's customers subscribed to five or more of its modules at the end of the previous quarter, an improvement over 59% in the year-ago period. And now CrowdStrike is offering a generative AI cybersecurity solution to automate threat detection and prevention tasks, a move that the company believes will help customers reduce costs and drive speedy results.

With the application of AI in cybersecurity expected to grow at an annual pace of 24% through the end of the decade, CrowdStrike's move into this market could unlock yet another major growth opportunity for the company. All this indicates why the company is expected to maintain healthy levels of growth going forward.

CRWD Revenue Estimates for Current Fiscal Year Chart

CRWD Revenue Estimates for Current Fiscal Year data by YCharts

What's more, analysts anticipate CrowdStrike's earnings will increase at an annual rate of 39% for the next five years. It should be able to live up to those expectations thanks to the huge addressable opportunity it is targeting, which is why CrowdStrike could remain a top growth stock for a long time.

2. Zscaler

Shares of Zscaler have set the market on fire since the beginning of May 2023, jumping a whopping 61% as the company pre-announced its fiscal 2023 third-quarter results last month. The company's revenue and earnings easily exceeded its guidance, and this was enough to send the stock soaring.

Just like CrowdStrike, Zscaler also serves the fast-growing cloud security market. The company claims that its security cloud platform serves more than 150 data centers across the globe and has users in 185 countries. Additionally, Zscaler points out that more than 40% of Fortune 500 companies are its customers. Such a massive customer base allowed Zscaler to build an ARR base of over $1.5 billion, and the company still has a lot of room for growth.

Zscaler's revenue in the third quarter of fiscal 2023 came in at $419 million, a jump of 46% over the prior year. This solid jump was driven by an increase in Zscaler's customer base, as well as an increase in spending by existing customers. More specifically, the company saw a 20% increase in its new customer base last quarter compared to the year-ago quarter.

Additionally, it reported a dollar-based net retention rate of over 125%. This metric compares the spending by a company's customers at the end of a period to the spending by the same customer cohort in the year-ago quarter, so a reading of more than 100% means that Zscaler's customers spent more on its offerings.

Not surprisingly, the number of Zscaler customers with more than $1 million in ARR with the company increased 39% year over year in fiscal Q3. Zscaler sees tremendous growth opportunities within its existing customer base, pointing out on the company's June earnings conference call that it sees "a 6x upsell opportunity with our existing customers for protecting their users."

All this explains why Zscaler is expected to maintain solid levels of revenue growth in the next two fiscal years following an estimated jump of 46% in the current one to $1.59 billion.

ZS Revenue Estimates for Current Fiscal Year Chart

ZS Revenue Estimates for Current Fiscal Year data by YCharts

This impressive revenue growth is expected to translate into rapid earnings growth as well. According to consensus estimates, Zscaler's earnings could clock a compound annual growth rate of 62% for the next five years. So Zscaler could remain a top growth stock in the long run. That's why investors should consider buying it right now, as it is trading at 14 times sales, which is significantly lower than its five-year average price-to-sales ratio of 32.