Amazon.com, Inc. (AMZN)

Amazon started as a bookstore and became the everything store — then quietly became something even bigger: the company that rents computing power to the rest of the internet.

Jeff Bezos left a Wall Street hedge fund in 1994 with a plan to sell books online. He chose books because they were commoditized (every copy identical), the catalog was enormous (3 million titles vs 200,000 in a big bookstore), and no physical store could compete on selection. He packed boxes in his garage and drove them to the post office himself. Within two years, Amazon had $15 million in revenue.

Today Amazon operates three massive businesses. E-commerce (the online marketplace) generates the most revenue but thin margins. Amazon Web Services (AWS) — cloud computing launched in 2006 — generates the most profit, providing servers, databases, and AI infrastructure to millions of businesses from startups to Netflix to the CIA. Advertising (product search ads on Amazon.com) is the fastest-growing segment and nearly pure profit.

Amazon's moat is a flywheel that feeds itself. More sellers attract more buyers. More buyers attract more sellers. More volume enables lower prices. Lower prices attract more buyers. Prime membership (200+ million subscribers) locks customers in with free shipping, video streaming, and grocery delivery — making Amazon the default first place people look. For AWS, switching costs are enormous — migrating databases and applications off AWS takes years.

The key risk is margin compression. Amazon's retail business operates on razor-thin margins by choice (Bezos: "Your margin is my opportunity"). If AWS growth slows or competition from Azure/GCP intensifies, Amazon's overall profitability could suffer. Regulatory scrutiny over marketplace dominance and labor practices also looms.