The first US company to reach a $1 trillion market cap was Apple Inc.
Apple crossed the milestone during trading on August 2, 2018, when its share price rose enough to value the company at roughly $1 trillion. Market capitalization is calculated by multiplying a company’s share price by its total shares outstanding, so the figure changes constantly with the market.
Apple’s achievement reflected decades of growth from its Macintosh computer business into a consumer-technology giant built around the iPhone, App Store, Mac, iPad, and services. The iPhone, introduced in 2007, became the company’s dominant growth engine and helped transform Apple’s scale and profitability.
A common mix-up is confusing the first US company with the first company anywhere to reach the milestone. Saudi Aramco later became the first non-US company widely reported to pass $1 trillion, while other technology companies soon joined Apple above that threshold.