Amazon became the second U.S. company to reach a $1 trillion market capitalization, after Apple, in September 2018.
Amazon crossed the threshold on September 4, 2018, when its share price rose above the level required for a $1 trillion valuation. The company had started as an online bookseller but expanded into a broad retail marketplace, logistics network, digital-media business, and cloud-computing provider.
Amazon Web Services became a major source of growth and profit, supplying computing and storage infrastructure to businesses and public organizations. The company’s scale in e-commerce also supported its valuation, even though retail margins were often relatively low.
The $1 trillion figure refers to the value of Amazon’s outstanding shares. It does not mean Amazon had $1 trillion in cash or revenue. Microsoft and Alphabet reached the same broad valuation milestone afterward.