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. The Big Four each offer audit, assurance, taxation, management consulting, actuarial, corporate finance, and legal services to their clients. A significant majority of the audits of public companies, as well as many audits of private companies, are conducted by these four networks. Until the late 20th century, the market for professional services was actually dominated by eight networks which were aptly nicknamed the "Big 8"...