The makeup of the "big 4" depends on who you're talking to. The phrase is borrowed from accounting, where there really are just four megafirms (and a large numb

The makeup of the "big 4" depends on who you're talking to. The phrase is borrowed from accounting, where there really are just four megafirms (and a large number of "boutique" firms). People probably mean Microsoft, Google, and two of Facebook, Apple, and Amazon. In terms of market share, you probably also want to account for large but less cool organizations like Oracle, HP, Verizon, etc.