Who Owns Deloitte?

William Welch Deloitte opened his London accounting practice in 1845, becoming a pioneer of the profession and the first person appointed to independently audit a public company, the Great Western Railway, in 1849. The firm expanded internationally through the 20th century, establishing US operations in the 1890s.

The modern global network took shape through mergers: Deloitte, Haskins & Sells combined with Touche Ross in 1989 to form Deloitte & Touche, creating one of the era's giant accounting firms. The 2002 collapse of Arthur Andersen after the Enron scandal consolidated the industry into today's Big Four, and Deloitte emerged from that consolidation positioned to grow beyond audit into consulting.

That consulting bet made Deloitte the largest of the four. While regulators constrained audit-adjacent work, Deloitte built the industry's largest consulting and advisory businesses, spanning strategy (through the acquired Monitor Group in 2013), technology implementation, risk advisory, and tax. By the mid-2020s consulting and advisory lines generated the majority of global revenue, making Deloitte structurally different from audit-led rivals.

The US firm, Deloitte LLP, anchors the network as its largest member. For fiscal 2025 ended May 31, it reported $35.7 billion in US revenue, while the global network reported a record $70.5 billion aggregate and a workforce exceeding 473,000. Jason Girzadas has led the US firm as CEO since June 2023, overseeing an AI-focused investment program and a major global reorganization of member firm structures announced in 2024.