Deloitte Touche Tohmatsu Limited
Explore Deloitte Touche Tohmatsu
Core profile pages, annual revenue records, and related research hubs for this company.
Deloitte Touche Tohmatsu Limited
Explore Deloitte Touche Tohmatsu
Core profile pages, annual revenue records, and related research hubs for this company.
Company History
Founded 1845 in London, United Kingdom
William Welch Deloitte opened an accounting office in London in 1845. The modern Deloitte network took shape through the histories and mergers of Deloitte, Haskins & Sells, Touche Ross, and Tohmatsu.
William Welch Deloitte opens an accounting office in London, establishing the Deloitte lineage.
George Touche establishes a predecessor firm that later becomes part of the Deloitte & Touche lineage.
Nobuzo Tohmatsu helps establish the Japanese firm that becomes part of Deloitte's global network identity.
Deloitte Haskins & Sells and Touche Ross combine to form Deloitte & Touche in a major professional-services merger.
The global network increasingly uses the Deloitte brand across member firms and service lines.
Joe Ucuzoglu becomes Deloitte Global Chief Executive Officer.
Deloitte reports $70.5B in aggregate global revenue for FY2025.
Deloitte acquired Monitor Group, a strategy consulting firm founded by Michael Porter, out of bankruptcy to add top-tier strategy consulting capabilities to its advisory practice. Monitor had gone bankrupt in 2012 following the loss of major client revenue during the financial crisis, but its brand and talent were valuable assets.
Deloitte acquired ConvergEx, a technology solutions provider for the financial services industry, to strengthen its financial services technology advisory and implementation capabilities at a time when capital markets firms were investing heavily in trading infrastructure and compliance systems.
Touche Ross merged with Deloitte Haskins & Sells in 1989 to form Deloitte & Touche, combining two of the Big Eight accounting firms as the profession was consolidating. The merger was driven by competitive pressure from the larger Arthur Andersen and Price Waterhouse firms and created a combined entity with greater global reach and client scale.
William Welch Deloitte founded his firm in the 19th century; later mergers created the global Deloitte network known today.
Combinations with Touche and international network formation made Deloitte one of the Big Four professional services giants.
Advisory and technology consulting expanded growth beyond audit, intensifying competition with Accenture and peers.
This Deloitte history page covers founding, mergers, and the modern multidisciplinary services model.