Cathie Wood is known for her propensity to buy growth stocks that have the chance to disrupt their industries while also making early investors rich. And that means she's a big buyer of biotech stocks via her ARK Innovation ETF (ARKK 1.05%). She's been particularly busy buying Intellia Therapeutics (NTLA 3.70%) and Ginkgo Bioworks (DNA 10.60%) this summer, making them companies that growth investors should want to know about now.

As with many of her other picks, Wall Street analysts estimate, on average, that both stocks could more than double within a year, though both lost value and underperformed the market over the last 12 months. Let's investigate what's driving their estimates and why Wood can't get enough of these two stocks.

1. Intellia Therapeutics

As an early-stage biotech stock years from having any shot at selling a medicine, Intellia Therapeutics is a high-risk, high-reward style investment that's a great fit for Cathie Wood. Wood most recently bought the stock on Aug. 31, as well as a bevy of other times in the preceding weeks and months. At the moment, it accounts for 2.4% of the ARK Invest portfolio. Wall Street estimates that its shares will fly to the tune of 121%, and its upcoming catalysts are doubtlessly the reason.

Before the end of this year, it plans to publish more data from its phase 1 trial that's investigating whether its gene-editing therapy is helpful in treating transthyretin amyloidosis (ATTR), a rare and eventually fatal multi-organ genetic disease affecting as many as 500,000 people worldwide. That program is intensely watched because Intellia's approach is to knock out defective copies of the relevant genes, thereby (hopefully) permanently curing patients in the process.

While it isn't the only company pursuing such an approach for genetic illnesses, the stakes are quite high. If Intellia can do what it aims, it'll mark the official start of a new era of medicine in which gene-editing technology is harnessed to improve human health in ways previously thought impossible.

The company also hopes to file the paperwork for its phase 2 study before 2024 and start talks with regulators at the Food and Drug Administration (FDA) about a future phase 3. But the star of the show will be its data update, which it hasn't provided any details on as of yet.

It's entirely feasible that its shares will double overnight if the data looks favorable as it would portend future opportunities to develop medicines for diseases with larger addressable markets while validating that the technology works safely and effectively. Of course, a failure would ding the stock.

However, given the biotech's cash and equivalents of $908 million and its 2022 operating expenses of only $510 million, it can afford to try developing something else if ATTR looks like a no-go.

2. Ginkgo Bioworks

As a services-based biotech, Ginkgo Bioworks is chasing an entirely different business model from a drug developer like Intellia. Rather than doing research and development (R&D) activities to advance its internal programs, with the aim of commercialization, this company helps other businesses design and manufacture economically valuable cells, like specialized yeasts for brewing alcohol or even symbiotic bacteria that help crops to be hardier.

It has a chance of becoming profitable, provided it can make more money from its collaborations than it spends in developing the associated cell products. But it's nowhere near profitable at the moment.

Cathie Wood last bought Ginkgo stock on Aug. 21, but she's been a consistent buyer for quite some time now. Her position is worth around 2.7% of the portfolio, which makes it the 13th-largest holding. Such a commitment indicates a high level of confidence in the company's future.

And Wall Street agrees. While analysts have changed their minds frequently, slashing and then increasing their estimates for the stock's performance, over the last three months, their average prediction has been for it to rise by 119%.

So, what's driving these heady growth estimates? In a word, momentum. Thanks to collaborations with big pharma companies like Merck and Novo Nordisk, among many other businesses you've definitely heard of, Ginkgo's services revenue is up by 72% year over year as of Q2, reaching $44 million.

It also increased its number of collaboration programs by 44%, reaching a total of 105. More collaborations are likely on the way, which is key because management thinks there are economies of scale in serving demand, which will drive down its costs the more programs it has to work on.

In the long term, if that's true, it should reward early investors richly as Ginkgo will be a profitable -- and likely very large -- biotech services provider. But investors might need to wait a few years for its efficiency to actually start improving and benefiting shareholders.