It’s the classic deserted desert island scenario: I have to pick just one stock that I would buy today and then hold forever. I can’t move the goalposts by picking an exchange-traded fund (ETF) and I’m not planning to build a portfolio around this name.

It’s just one stock, and it will be my only investment for all time. All alone.

Mind you, I don’t recommend actually doing this with real money. Diversification matters, and no stock is absolutely risk-free. This is just a fun little thought experiment.

That being said, I could imagine entrusting my life savings to Amazon (AMZN 0.23%) today. Here’s how Jeff Bezos’ empire earned this rare honor.

I’m almost cheating — Amazon is like an ETF in disguise

If I can’t diversify my single-stock holding with an ETF, I’ll go with a leader across many different industries instead. Amazon fits the bill to perfection:

• With $137 billion of second-quarter sales, Amazon is a world-leading e-commerce titan.

• The Amazon Web Services (AWS) division didn’t exactly invent cloud computing, but it was an early provider in that field and remains a top name today. In the second quarter of 2025, AWS sales landed at $30.9 billion.

• Within the AWS envelope, you’ll find Amazon in several distinct positions of leadership. AWS is a top choice for artificial intelligence (AI) services, both on the systems training and real-time AI operations sides. Amazon’s digital advertising platform proved its worth on September 10 when it won the Netflix (NFLX 1.59%) ad-selling contract in 11 key markets.

• The massive e-commerce business requires a world-class shipping infrastructure, and Amazon is reselling these services to other online retailers nowadays.

That’s an online shopping portal, the world’s largest cloud computing service, top-notch advertising and AI services, and a winning physical logistics business — all wrapped in a single stock. That’s a pretty respectable single-business impersonation of a truly diversified investment portfolio.

When corporate synergy actually works

Amazon’s conglomerate structure comes with some unique benefits, too. Let’s play some buzzword bingo! Here are a few examples of corporate synergy with material benefits:

• AWS started as a little side gig, trying to make some money from the online infrastructure Amazon had installed and wasn’t always using. Now, it’s the other way around — any time Amazon’s retail business needs a digital tool (web server space, AI support, data analytics, ad-tech innovation…) AWS is the obvious in-house choice.

• Profits collected in the incredibly lucrative AWS division can be deployed in other projects. The shipping infrastructure saw massive expansion in the 2020-2022 era, for example. This push would not have been possible without the AWS segment’s booming profits.

• Amazon’s advertising platform benefits from the enormous bank of transaction data in the company’s own retail operations.

• The Prime customer loyalty program has become the digital glue that holds Amazon’s growth drivers together. Come for the free one-day shipping, stay for the award-winning Prime Video shows or the Echo/Alexa smart home system. Or, you know, the other way around.

The Prime directive: Borrowing brilliance from Costco

Speaking of Prime, by the way, that’s Amazon borrowing a page out of the Costco Wholesale (COST -0.05%) playbook. Costco’s operations would lose money without its membership program. With it, you make Costco shoppers more likely to choose that store (because I’m paying for that precious card anyway) while generating a rich stream of nearly pure profit.

Amazon uses Prime in a similar fashion — unlocking synergies and collecting profits as a direct result.

Image source: Getty Images.

Wrapping up this trillion-dollar thought experiment

If you’re skipping to the final chapter of my Amazon analysis, here’s the short version.

I expect Amazon to remain a business leader for decades to come. It’s among the 5 most valuable businesses today, measured by market cap, and I see no reason why that would change in the long run.

This little trillion-dollar stock should serve me well on that hypothetical desert island.