American stock exchanges currently host eight American technology companies with valuations of $1 trillion or more, but only three have graduated into the $3 trillion club so far:Apple: $3.7 trillionNvidia: $3.3 trillionMicrosoft: $3.3 trillionAmazon (AMZN -4.60%) is the world's fourth-largest company, at this writing, with a market capitalization of $2.4 trillion. Its stock has soared by more than 50% this year and trades at an all-time high. The company's strong cloud growth, soaring profits, and leadersh ...