Alphabet became the fourth US firm to surpass a US$1 trillion market capitalization in January 2020.
Alphabet, Google's parent company, crossed the milestone during trading on January 16, 2020. It followed Apple, Microsoft, and Amazon, which had already exceeded the trillion-dollar threshold. Market capitalization is calculated by multiplying a company's share price by its outstanding shares, so the figure changes continuously during trading.
Alphabet was created in 2015 as part of a corporate restructuring that placed Google and several other businesses under a new holding company. Google remained Alphabet's dominant business, with advertising providing the largest share of revenue, while units such as Google Cloud and Other Bets broadened the group's activities.
A common mix-up is to call Alphabet simply Google in this ranking. Google is the principal operating company, but Alphabet is the publicly traded parent whose shares determine the quoted market capitalization.