While many stocks rebounded sharply in 2023, all three major U.S. financial indexes remain below their all-time highs. The blue chip Dow Jones Industrial Average (DJINDICES: ^DJI) is down nearly 8%, the broad-based S&P 500 (SNPINDEX: ^GSPC) is down 10%, and the tech-centric Nasdaq Composite (NASDAQINDEX: ^IXIC) is down about 17%.

History says all three indexes will eventually reach new highs, meaning there are buying opportunities in the market right now. Investors who have $1,000 available that isn't needed to pay monthly bills, bolster an emergency fund, or pay down short-term debt should consider splitting the sum evenly between Zscaler (ZS 1.28%) and SolarEdge Technologies (SEDG 2.81%), provided neither position exceeds 2% of their portfolios.

Here's why these two growth stocks are worth buying.

1. Zscaler

Zscaler runs the largest network security cloud in the world. Its security service edge (SSE) platform modernizes corporate networks by moving traffic inspection and policy enforcement to the cloud. That eliminates the need for costly on-premises appliances, and it provides customers with superior security and a better user experience.

Zscaler benefits from its immense scale. As the largest network security cloud, its SSE platform inspects over 320 billion transactions daily, and it captures more than 500 trillion security signals in the process. Those data points feed its artificial intelligence (AI) models, creating a network effect that results in superior threat protection for customers, according to CEO Jay Chaudhry.

That value proposition has caught the attention of industry analysts. IT consultancy Gartner recently recognized Zscaler as a leading SSE vendor, and International Data Corp. recognized the company as a leader in zero-trust network access.

Those accolades came alongside strong financial results in the fiscal fourth quarter (ended July 31). Revenue climbed 43% year over year to $455 million, and non-GAAP (generally accepted accounting principles) earnings soared 156% to $0.64 per diluted share.

Zscaler values its addressable market at $72 billion, and the company should benefit from the growing demand for zero-trust security. Notably, Gartner says enterprise penetration of SSE platforms will reach 80% by 2025, up from 20% in 2021. Zscaler is well-positioned to monetize that tailwind, given its strong market presence.

Shares currently trade at 13.8 times sales, a major discount to the five-year average of 30.5 times sales, and a reasonable price to pay for this cybersecurity stock.

2. SolarEdge Technologies

SolarEdge is the second-largest manufacturer of solar inverters in the world and the largest manufacturer outside of China. The company is best known for developing power optimizers, devices that maximize solar production by mitigating losses related to panel mismatch, but it also provides adjacent products for residential and commercial use, including batteries and cloud-based monitoring software.

SolarEdge reported solid financial results in the second quarter. Revenue increased 36% to $728 million, and non-GAAP earnings soared 176% to $2.62 per diluted share. However, management expects growth to slow substantially in the near term due to higher interest rates and excess inventory. Guidance implies revenue growth ranging from 5% to 10% in the current quarter.

That gloomy outlook sent the stock into a free fall, and SolarEdge has seen its share price drop 40% since the beginning of August. But sellers are sleeping on the big picture, much to the benefit of patient investors. Temporary headwinds notwithstanding, renewable energy is an imperative, and SolarEdge should be a major beneficiary as solar energy sees greater adoption around the world.

Indeed, Grand View Research says the solar energy systems market will grow at 16% annually through 2030, but SolarEdge should grow even faster due to its strong presence in the inverter market. The company is also building on its brand authority to enter adjacent areas like commercial and residential energy storage, electric vehicle charging, and energy management software.

On that note, Wall Street is exceptionally bullish on SolarEdge. The median price target of $290 per share implies a 113% upside from its current price, and Morgan Stanley says SolarEdge could grow revenue at 21% annually through the end of the decade. In that scenario, its current valuation of 2.1 times sales -- the cheapest price-to-sales multiple in more than four years -- would be an absolute bargain, especially when the five-year average is 5.8 times sales.

Investors should feel confident in buying this growth stock today.

How investors should think about position sizing

The $1,000 lump sum mentioned earlier is somewhat arbitrary. Investors should make asset allocation decisions based on their conviction and the size of their portfolio. When I purchase a new stock, I like to start small and build my position over time through dollar-cost averaging. Additionally, my initial stake never exceeds 2% of my total portfolio.