Apple became the first publicly traded company valued at $1 trillion in 2018 and later reached $2 trillion in 2020.
The first milestone was reached in August 2018 as Apple's share price rose and its total outstanding shares produced a market capitalization of about $1 trillion. The second milestone arrived approximately two years later, showing how quickly investor valuations can change for a dominant technology company.
Apple's valuation growth was tied to the worldwide iPhone business and to additional revenue from services, accessories, and wearables. Its financial scale also reflected the strength of its retail, developer, and supply-chain ecosystem.
The answer is the company rather than a product: the iPhone helped drive Apple's market value, but the market capitalization belongs to Apple Inc. as a whole.