Imagine a world where your investment portfolio could only consist of one stock. What stock comes to mind? A tech giant? A legendary consumer-goods company? Maybe a promising biotech?

Now, strictly speaking, limiting oneself to a single stock violates one of The Motley Fool's core philosophical principles of buying and holding 25 or more stocks. Nevertheless, it's a fun thought exercise. And for me, the choice is easy: It's Amazon (AMZN 1.16%).

Person sitting at a desk using a desktop computer.

Image source: Getty Images.

One company, multiple businesses

Here's the main reason I would own Amazon if I could only own one stock: Its large and varied revenue streams provide its shareholders with diversity -- even if they own no other stocks. That's because Amazon is:

  • The world's largest e-commerce company.
  • The biggest cloud computing company.
  • Operator of one of the largest subscription-based models (Amazon Prime).
  • A generator of billions of dollars from online advertising.

That's to say nothing of other endeavors that Amazon is pursuing, such as smart devices (like Echo and Alexa), music and video streaming, and healthcare. This mixture of revenue sources and unrelated units would be invaluable for an investor who -- for whatever reason -- could only own one stock.

Amazon's business is revving up

The second reason this is the best stock to own -- if you could only own one stock -- is that Amazon's business looks like it's on the upswing. The COVID-19 pandemic was a boon for Amazon. Homebound shoppers loaded up their virtual carts, and Amazon's share price skyrocketed.

However, the company has been dealing with something of a hangover since the pandemic has waned. High inflation, energy costs, and overstaffing kept a lid on Amazon's shares in 2022.

Yet this year, the stock is on fire. Shares are up 35% year to date. And the company recently reported excellent first-quarter results, highlighted by:

  • Total revenue of $127 billion, which topped estimates
  • Amazon Web Services (AWS) revenue of $21 billion, up 16% from a year earlier
  • Advertising revenue of $9.5 billion, ahead of expectations of $9.1 billion

What's more, CEO Andy Jassy noted that the company's investments in machine learning continue to pay off: "Our advertising business continues to deliver robust growth, largely due to our ongoing machine learning investments that help customers see relevant information when they engage with us, which in turn delivers unusually strong results for brands."

Amazon remains a no-brainer stock to own

In summary, Amazon is a perfect mix of variety, growth, and results. Multifaceted revenue streams provide redundancy. A weak economy or competitive pressures might hamper growth in one segment, but the company often gets the last laugh as a new segment catches fire thanks to a new product or innovation.

At any rate, it remains one of the largest and best-run businesses out there. And, for me, if I could only buy one stock, it would be Amazon.