The Big 4 firms in cybersecurity are Deloitte, PwC, EY and KPMG. Updated: ****. The term "Big 4" refers to the four largest global accounting and professional-services networks, not to an official cybersecurity ranking. Each firm has large practices covering cybersecurity consulting, risk, managed services and incident response.
| Firm | Main cybersecurity strengths | Typical services |
|---|---|---|
| Deloitte | Cyber transformation, defense and managed operations | Cyber strategy, cloud and application security, threat intelligence, incident response, zero trust and managed cybersecurity |
| PwC | Cyber risk, digital identity, governance and managed services | Cyber defense, identity, cloud security, risk assessments, compliance and continuous monitoring |
| EY | Cyber transformation, privacy, compliance and threat response | Cyber strategy, data protection, identity, threat detection, security testing, incident response and resilience |
| KPMG | Cyber governance, transformation and enterprise risk | Cyber strategy, governance, defense, incident response, cloud security, AI security and managed services |
Which Companies Make Up the Big 4?
The four firms are Deloitte, PwC, EY and KPMG. Their services overlap, but each firm places different weight on areas such as cyber risk, privacy, managed operations, governance and incident response.
1. Deloitte
Deloitte has a broad cybersecurity practice covering cyber defense and resilience, cyber strategy and transformation, and Cyber Operate managed services. Its listed capabilities include cloud security, application security, zero trust, operational technology security, threat intelligence and incident response.
Deloitte may suit organizations that need:
- Large-scale cyber transformation
- Managed detection and response
- Cloud, application or identity security
- Complex incident-response support
- Enterprise-wide security programs
- Support across multiple countries or business units
Deloitte reports that its cybersecurity practice includes more than 35,000 practitioners, serves clients in more than 150 countries and territories, and has more than 30 years of cybersecurity experience. These figures come from Deloitte and are not an independent industry ranking.
2. PwC
PwC's published cybersecurity capabilities include cyber defense, digital identity, cyber risk and cloud security. Its work often connects cybersecurity with technology risk, internal controls, privacy and business resilience.
PwC may suit organizations that need:
- Cyber risk and control assessments
- Identity and access management
- Regulatory compliance support
- Cloud risk and governance
- Board-level cybersecurity advice
- Managed cybersecurity services
3. EY
EY provides services covering cybersecurity transformation, privacy, cyber risk, threat detection, identity, security testing and incident response. Its published practice areas include data protection and privacy, cyber threat management, detection and response, compliance and resilience.
EY may suit organizations that need:
- Privacy and data-protection programs
- Cybersecurity compliance
- Threat detection and response
- Digital and customer identity services
- Security testing
- Forensic investigations
- Regulatory support after an incident
EY's cyber-response practice combines cybersecurity, IT forensics and investigative support for incidents such as ransomware, business email compromise and data theft.
4. KPMG
KPMG groups its cybersecurity services into strategy and governance, cyber transformation, cyber defense and cyber response. Its offerings also cover cloud security, AI security, managed services and operational technology.
KPMG may suit organizations that need:
- Cyber governance and risk management
- Security operating-model design
- Regulatory and compliance support
- Cloud and artificial-intelligence security
- Incident response
- Cyber transformation
- A close connection between cybersecurity and enterprise risk
KPMG describes its services as covering the cybersecurity lifecycle from assessment and strategy through implementation, monitoring and incident response.
Are the Big 4 Cybersecurity Companies the Same as Cybersecurity Vendors?
No. Deloitte, PwC, EY and KPMG are professional-services firms that advise on, implement, operate and investigate security programs.
Their cybersecurity work can include:
- Assessing cyber risk
- Designing security strategies
- Implementing security technologies
- Improving governance and compliance
- Operating security monitoring services
- Investigating and responding to breaches
- Securing cloud environments, identities, applications and data
Companies such as Microsoft, Palo Alto Networks, CrowdStrike, Cisco and Fortinet primarily develop cybersecurity platforms, software and network-security products. The cybersecurity market has no universally accepted "Big 4" ranking for those vendors.
Which Big 4 Cybersecurity Firm Is Best?
There is no single best firm for every organization. The right choice depends on the required service, industry experience, geography, technology environment and delivery model.
A practical starting point is:
- Deloitte: Global scale, broad technical coverage or large transformation programs
- PwC: Cyber risk, controls, digital identity, cloud governance or compliance
- EY: Privacy, regulatory response, cyber resilience, threat detection or digital identity
- KPMG: Governance, enterprise risk, transformation or board-level cyber oversight
Compare firms using these criteria:
- Experience in your industry
- Expertise with your security stack
- Incident-response and managed-service capabilities
- Availability of local delivery teams
- Independence and possible audit conflicts
- Clear pricing and scope of work
- Evidence of work with organizations of a similar size
Bottom Line
The term "Big 4" identifies four professional-services networks with large cybersecurity practices. Use the label as a starting point, then compare each firm's industry experience, technical coverage, location, delivery model and potential conflicts before making a decision.