Alphabet’s market capitalization is calculated from its listed Class A and Class C shares.
Alphabet’s Class A shares trade under GOOGL and generally carry one vote per share. Class C shares trade under GOOG and generally carry no voting rights. Alphabet also has Class B shares with enhanced voting power, but those shares are not publicly traded.
The separate share classes allow Alphabet’s founders and other insiders to retain substantial voting influence while public investors buy listed shares. The company created the structure during Google’s 2014 stock split and later parent-company reorganization.
When financial websites report Alphabet’s total market capitalization, they combine the value of its relevant share classes rather than looking at only one ticker. This can make the displayed valuation differ slightly between data providers if they use different timing or share-count estimates.