The Big Four is the nickname used to refer collectively to the four largest professional services networks in the world, consisting of the global accounting networks Deloitte, Ernst & Young, KPMG and PwC. The four networks are often grouped together for a number of reasons; they are each comparable in size relative to the rest of the market, both in terms of revenue and workforce; they are each considered equal in their ability to provide a wide scope of professional services to their clients; and, among those looking to start a career in professional services, particularly accounting, they are considered equally attractive networks to work in, because of the frequency with which these firms engage with "Fortune" 500 companies.