Deloitte Touche Tohmatsu Limited

Deloitte is a multinational professional services network that provides audit, assurance, tax, consulting and advisory services to clients across a range of sectors. It is commonly recognised as one of the Big Four accounting firms worldwide. The organisation operates under the aliases Deloitte, Deloitte & Touche and Deloitte Touche Tohmatsu Limited, with its headquarters located in the United Kingdom. Its service offerings are designed to help organisations manage risk, improve performance and navigate complex regulatory environments.

Deloitte distinguishes itself through an integrated model that combines deep industry knowledge with technical expertise in areas such as financial reporting, risk management, digital transformation and strategy. The firm maintains a strong focus on innovation, investing in emerging technologies and data analytics to enhance the value delivered to clients. Its professionals often hold specialised qualifications and are subject to rigorous independence and quality standards required of audit firms. These attributes have positioned Deloitte as a leading advisor for corporations, governments and nonprofit organisations.

In recent years Deloitte has been involved in notable cybersecurity incidents that have tested its incident response capabilities. In May 2023 the Clop ransomware gang exploited a zero‑day vulnerability in MOVEit file transfer software and listed Deloitte on its data leak site, although the firm stated that its use of the vulnerable software was limited and an investigation found no evidence of client data being compromised. Earlier, in October 2016, a breach of Deloitte’s global email server occurred after an administrator account lacking two‑factor authentication was compromised, granting attackers prolonged access to internal communications. The firm responded to both events with investigations, notifications to affected parties and reinforcement of security controls. These episodes underscore the importance of robust cybersecurity practices within large professional services organisations.