The Big 4 are the largest accounting and auditing firms in the world: Deloitte LLP (Deloitte), PricewaterhouseCoopers (PwC), Ernst & Young (EY) and Klynveld Peat Marwick Goerdeler (KPMG). They’re so big that their joint revenue in 2024 was—you guessed it—$212 billion.16 Jun 2025