Warren Buffett is undoubtedly one of the most accomplished business leaders of our time. Since taking control of Berkshire Hathaway in 1965, he has turned the former textile company into a $670 billion conglomerate, and Berkshire stock has nearly doubled the performance of the S&P 500.

Meanwhile, Buffett has also earned a reputation as one of the greatest investors in history. Berkshire's equity investment portfolio was worth $306 billion at the end of the third quarter, and unrealized gains accounted for more than half of that total. Given Buffett's track record, investors should always keep an eye on the stocks Berkshire (and its subsidiaries) own.

Here are two growth stocks to buy now and hold forever.

Amazon: Down 54% from its high

Amazon (AMZN 0.58%) has seen its share price plunge 54%, marking its sharpest decline in the past decade. Throughout 2022, the retail giant has fought a losing battling with rising prices, which have been a headwind to consumer spending and an accelerant for operating expenses. To that end, third-quarter revenue climbed just 15% to $127 billion and net income dropped 10% to $0.28 per diluted share.

On the bright side, Amazon's growth is set to reaccelerate when consumer spending rebounds and cost pressures diminish. In the meantime, shares currently trade at 1.7 times sales -- the cheapest valuation in five years -- meaning investors have a rare opportunity to buy this FAANG stock at a bargain price.

The bull case can be broken into three parts. First, Amazon runs the most popular online marketplace in the world, and it holds nearly 40% market share in U.S. e-commerce. Second, Amazon Web Services (AWS) is the market leader in cloud infrastructure and platform services, holding twice as much market share as the next-closest cloud vendor. Third, Amazon is the third-largest digital advertiser in the U.S., and it is gaining market share, while the leaders -- Alphabet's Google and Meta Platforms -- are losing market share. Better yet, Amazon is the fourth-largest digital ad company on the planet, and it nearly led the world in ad revenue growth in 2021.

In a nutshell, Amazon enjoys a strong position in three different markets, all of which are growing quickly. Ameco Research says global e-commerce sales will grow at 13% annually to reach $15 trillion by 2030. Grand View Research says cloud computing spend will increase at 16% annually to reach $1.6 trillion by 2030. And Precedence Research says global digital ad spend will grow at 9% annually to reach $1.3 trillion by 2030. For all of those reasons, this Warren Buffett stock is a screaming buy.

Nvidia: Down 55% from its high

Some investors may be confused to see chipmaker Nvidia (NVDA -1.99%) discussed here. After all, Buffett does not own a single share of Nvidia through Berkshire Hathaway. But Berkshire does own reinsurance company General Re and its subsidiary New England Asset Management (NEAM), and NEAM started a position in Nvidia during the second quarter.

Nvidia has struggled amid the difficult economic environment. Demand for graphics and data center chips has softened in response to high inflation, and that has led to disappointing financial results. Third-quarter revenue dropped 17% to $5.9 billion and net income plunged 72% to $0.27 per diluted share. That news, coupled with weak fourth-quarter guidance, has knocked the share price down by 55%.

However, those headwinds are temporary, and the bull case for the semiconductor company is still rock solid: Nvidia is the leader in workstation graphics and accelerated data center computing, holding more than 90% market share in both categories, and its brand name is synonymous with emerging technologies like artificial intelligence (AI) and the metaverse.

Better yet, Nvidia has reinforced its leadership in graphics and accelerated computing with a growing portfolio of subscription software, which leaves room for margin expansion. For instance, Omniverse software allows creators to collaborate on metaverse applications, and Nvidia AI Enterprise software allows developers to build AI applications that address use cases across virtually any industry, including autonomous robots for manufacturing and logistics, recommender systems for retail, and intelligent avatars for customer service.

Finally, Nvidia has consistently showcased a tremendous capacity for innovation, and that quality should keep it at the forefront of the graphics and data center computing industries for years to come. For instance, Nvidia is set to debut its first central processing unit (CPU) next year. Of course, the company is best known for its graphics processing units (GPUs), but the soon-to-launch Grace CPU will expand its utility in data centers. Grace is specifically designed for "very large data processing at very high speeds," according to CEO Jensen Huang, meaning the chip will be valuable in compute-intensive workloads like AI.

On that note, Nvidia puts its addressable market at $1 trillion, leaving a long runway for growth. And with shares trading at 13.4 times sales, a slight discount to the five-year average of 16.9 times sales, now is a good time to buy a small position in this growth stock.