Ernst & Young

01. Findings

In July 2026, EY disclosed a significant data breach involving a third-party IT service management platform used for tax-related work [9]. Unauthorized parties accessed the platform between March 28 and April 12, 2026, downloading documents containing client tax information, Social Security numbers, and financial account codes [13]. EY detected anomalous activity on April 23, 2026, and engaged an independent cybersecurity firm to investigate [13]. The firm filed breach notifications with the California and Vermont Attorneys General in mid-July 2026. EY states that the unauthorized access has been stopped and systems are secure.

02. Events

• [legal] Proposed Class Action Lawsuit

  A proposed class-action lawsuit was filed in New York federal court alleging EY failed to protect sensitive client tax and financial information exposed in the breach.

  Jul 20, 2026, 12:00 AM · Source

• [breach] EY Third-Party IT Support Platform Data Breach

  Unauthorized access to a third-party IT service management platform between March 28 and April 12, 2026, exposed client tax, financial, and personal information. EY detected activity on April 23, 2026, and filed breach notifications in July 2026.

  Jul 15, 2026, 12:00 AM · Source

• [breach] EY Data Breach via Third-Party Platform

  Unauthorized access to a third-party IT support platform used for tax work, exposing client tax, financial, and personal information between March 28 and April 12, 2026.

  Jul 15, 2026, 12:00 AM · Source

• [leadership] Janet Truncale Appointed Global Chair and CEO

  Janet Truncale was elected as the next EY Global Chair and CEO, effective July 1, 2024.

  Jul 1, 2024, 12:00 AM

03. AI Risk

How this vendor uses AI/ML with customer data - model providers, training stance, subprocessors, and relevant DPA language when publicly documented.

AI exposure tier: Moderate AI Exposure

EY utilizes AI in its service offerings, such as the EY-Parthenon Competitive Edge platform for AI-led M&A intelligence and EY.ai Workforce for HR automation [17]. The firm also discusses the use of GenAI in low-code/no-code platforms for generating code snippets and data models [21]. However, specific details on whether EY trains its own models on customer data or the specific LLM providers used are not publicly disclosed in the provided sources.

Training on customer data

Training stance unknown

04. Company

Ernst & Young (EY) is a multinational professional services network headquartered in London, England, and is one of the Big Four accounting firms alongside Deloitte, KPMG, and PwC [1]. Founded in 1989 through the merger of Ernst & Whinney and Arthur Young & Co., the firm provides assurance, tax, transaction, and advisory services globally [1]. EY reported global revenue of US$51.2 billion for fiscal year 2024 and employs approximately 392,995 to 406,209 people worldwide [1]. Janet Truncale serves as the Global Chair and CEO, having assumed the role effective July 1, 2024 [1].

05. Product

EY offers a suite of technology platforms and advisory services, including the EY Digital Energy Enablement Platform (DEEP), which combines Microsoft’s cloud platform with industry expertise. Other products include EY-Parthenon Competitive Edge for AI-led M&A intelligence, WAMapps for risk management in asset management, and EY Nexus for banking transformation. The firm also provides EY.ai Workforce, an AI-enabled digital worker platform for HR functions. EY’s competitors in the professional services and consulting space include Deloitte, PwC, KPMG, and Accenture.

06. Recent News

Recent news focuses on the July 2026 data breach disclosure and subsequent legal actions. EY notified clients and regulators that sensitive personal and financial data was compromised via a third-party support ticket system. A proposed class-action lawsuit was filed in New York federal court, alleging EY failed to protect client information. The lawsuit claims that support tickets contained attachments with client tax information, which were downloaded by unauthorized actors. EY has been active in incident response and remediation efforts since detecting the breach in late April 2026.

07. Dependencies

Fourth parties this vendor relies on - subprocessors, infrastructure, and integrations surfaced from public sources.

• Third-party IT service management platform

  SubprocessorSource →

• Microsoft

  InfrastructureSource →

08. Competitors

Vendors offering a similar product or service - for side-by-side comparison, not a ranking.

• Accenture

  accenture.com

  Vet this vendor →

• Deloitte

  deloitte.com

  Vet this vendor →

• PwC

  pwc.com

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• KPMG

  kpmg.com

  Vet this vendor →

10. Vendor response

Content in this section is vendor-supplied and does not alter Vendorisk.ai's risk tier or evaluation.

11. Assessment history

1. 8/19/2026, 10:27:29 PM · High · 100

Risk delta is hidden until two stored snapshots can be compared.

12. Targeted questions

13. Sources

1. [1] Ernst & Young (EY) is a multinational professional services network headquartered in London, England, and is one of the Big Four accounting firms. Ernst & Young - Wikipedia
2. [2] EY reported global revenue of US$51.2 billion for fiscal year 2024 and employs approximately 392,995 people. Ernst & Young - Wikipedia
3. [3] Janet Truncale serves as the Global Chair and CEO, effective July 1, 2024. Ernst & Young - Wikipedia
4. [4] EY offers technology platforms including EY DEEP, EY-Parthenon Competitive Edge, WAMapps, and EY Nexus. Technology platforms and products | EY - Global | EY - US
5. [5] EY.ai Workforce is an AI-enabled platform providing digital workers for HR tasks. Technology platforms and products | EY - Global | EY - Global
6. [6] EY’s competitors include Deloitte, PwC, KPMG, and Accenture. Top 10 Ernst & Young Alternatives & Competitors in 2026 - G2
7. [7] EY disclosed a data breach involving a third-party IT service management platform used for tax-related work. EY data breach: what happened and what's at risk | UpGuard