EY vs Sia Partners: full comparison for 2026
Quick verdict
EY (4.2/5) edges ahead of Sia Partners (4.1/5) overall. EY is the better choice for enterprises building AI risk into existing controls. Sia Partners is the stronger option for utilities and insurers wanting regulatory-minded advice. The right choice depends on how independent you need the advice to be, your regulatory exposure, and your budget.
EY vs Sia Partners: head-to-head summary
| Criterion | EY | Sia Partners |
|---|---|---|
| Founded | 1989 | 1999 |
| HQ | London, UK | Paris, France |
| Team size | ~400,000 | ~3,500 |
| Rating | 4.2 / 5 | 4.1 / 5 |
| Primary differentiator | AI risk work folded into existing technology risk and controls programs | Sector regulatory practices applied to AI governance, plus its own Heka.ai tools |
| Pricing model | Engagement fees per scope; rates not published | Consulting fees; rates not published |
| Min. engagement | Not disclosed | Not disclosed |
| Primary tech stack | EU AI Act, NIST AI RMF, GDPR | EU AI Act, GDPR, DORA |
| Industries served | Financial services, Insurance, Public sector, Energy, Consumer | Energy & utilities, Banking, Insurance, Public sector, Telecom |
EY vs Sia Partners: overview
EY
EY was formed by the 1989 merger of Ernst & Whinney and Arthur Young and employs about 400,000 people. Its advisory teams cover responsible AI, AI risk, and compliance programs, and its technology risk leaders have spoken publicly about how far real AI assurance still has to go. That candor is useful for buyers who want an honest view of what can be certified today. Like the rest of the Big Four, it sells implementation as well.
Sia Partners
Founded in Paris in 1999, Sia Partners now has roughly 3,500 consultants in about 20 countries. Its regulatory practices in energy, utilities, banking, and insurance carry over naturally to AI governance. The firm also sells Heka.ai, a catalog of AI software products, which can speed early results but makes its tool advice less neutral. It suits companies that want management consultants first and technologists second.
Services and capabilities: EY vs Sia Partners
| Capability | EY | Sia Partners |
|---|---|---|
| Readiness assessment | ✓ | ✗ |
| Use-case prioritization | ✗ | ✓ |
| TCO / ROI modeling | ✗ | ✗ |
| AI governance & EU AI Act | ✓ | ✓ |
| Build vs. buy advice | ✗ | ✗ |
| Independent audit or assurance | ✓ | ✗ |
| Roadmap any vendor can implement | ✗ | ✗ |
| Delivery capability after advice | ✓ | ✗ |
Frameworks and platforms: EY vs Sia Partners
| Framework / platform | EY | Sia Partners |
|---|---|---|
| EU AI Act | ✓ | ✓ |
| GDPR | ✓ | ✓ |
| DORA | N/A | ✓ |
| NIST AI RMF | ✓ | N/A |
| ISO/IEC 42001 | N/A | N/A |
| Azure | ✓ | N/A |
| AWS | N/A | N/A |
| Google Cloud | N/A | N/A |
Pricing comparison: EY vs Sia Partners
| Criterion | EY | Sia Partners |
|---|---|---|
| Minimum engagement | Not disclosed | Not disclosed |
| Engagement models | Fixed-scope assessment, Multi-use-case advisory, Audit or certification, Delivery team | Fixed-scope assessment, Multi-use-case advisory, Ongoing advisory |
| Rate transparency | Not public | Not public |
| Price tier | Mid-market | Mid-market |
Target audience comparison: EY vs Sia Partners
| Dimension | EY | Sia Partners |
|---|---|---|
| Best company size | Enterprise | Mid-market to enterprise |
| Best industries | Financial services, Insurance, Public sector | Energy & utilities, Banking, Insurance |
| Best use cases | Adding AI risk to an existing controls framework., Responsible AI policies for a large insurer. | AI governance for a regulated utility., DORA and AI Act planning at an insurer. |
| Typical project type | Fixed-scope assessment | Fixed-scope assessment |
EY vs Sia Partners: pros and cons
| EY | |
|---|---|
| + | Ties AI risk to controls frameworks finance teams already use |
| + | Realistic public view on the limits of AI assurance |
| + | Large global bench |
| - | Premium fees |
| - | Sells delivery alongside advice |
| - | Audit-client independence rules apply |
| Sia Partners | |
|---|---|
| + | Long regulatory experience in energy and finance |
| + | Change management is part of the offer |
| + | Ready-made tools for early wins |
| - | May favor its own Heka.ai products |
| - | Limited engineering depth for custom work |
| - | Smaller US presence |
Who should choose EY?
A typical fit: adding AI risk to an existing controls framework.
AI risk work folded into existing technology risk and controls programs. Minimum engagement is not publicly disclosed. Works best with clients in Financial services, Insurance, Public sector, Energy, Consumer.
Who should choose Sia Partners?
A typical fit: AI governance for a regulated utility.
Sector regulatory practices applied to AI governance, plus its own Heka.ai tools. Minimum engagement is not publicly disclosed. Works best with clients in Energy & utilities, Banking, Insurance, Public sector, Telecom.
Decision matrix: EY vs Sia Partners
| Your situation | Recommended choice |
|---|---|
| You want advice with no build contract attached | Sia Partners |
| Finance needs run costs before approving anything | Neither lists cost modeling; ask for a sample |
| Some of your use cases may be high-risk under the EU AI Act | Both cover AI Act classification |
| You need an outside check on a system already built | EY |
| You want the same firm to build what it recommends | EY |
| Your budget is at the lower end | Compare: EY (Not disclosed) vs Sia Partners (Not disclosed) |
| You need advisers in many countries at once | EY |
Use case fit: EY vs Sia Partners
| Use case | EY fit | Sia Partners fit | Winner |
|---|---|---|---|
| Adding AI risk to an existing controls framework. | Strong | Limited | EY |
| Responsible AI policies for a large insurer. | Strong | Limited | EY |
| AI governance for a regulated utility. | Limited | Strong | Sia Partners |
| DORA and AI Act planning at an insurer. | Limited | Strong | Sia Partners |
Verdict: EY vs Sia Partners
EY (4.2/5) is the stronger overall choice for most AI Advisory projects. AI risk work folded into existing technology risk and controls programs.
Sia Partners (4.1/5) is worth a look if you need DORA and AI Act planning at an insurer. If your situation matches that, Sia Partners is a competitive option.
Related comparisons
EY vs Sia Partners FAQ
Is EY better than Sia Partners?
EY (4.2/5) scores higher overall, but "better" depends on your use case. EY's strongest advantage: ties AI risk to controls frameworks finance teams already use. Sia Partners's strongest advantage: long regulatory experience in energy and finance.
How do EY and Sia Partners differ in pricing?
EY's pricing: engagement fees per scope; rates not published. Sia Partners's pricing: consulting fees; rates not published. Any hourly bands shown come from Clutch, not a published rate card, so a scoping call is still needed for a project quote.
Which is better for enterprise: EY or Sia Partners?
EY is the larger team and typically the better enterprise-scale choice. For very large programmes, verify team size and compliance coverage directly with each firm before shortlisting.
What are the main differences between EY and Sia Partners?
EY's primary differentiator is: AI risk work folded into existing technology risk and controls programs. Sia Partners's primary differentiator is: sector regulatory practices applied to AI governance, plus its own Heka.ai tools. They also differ in team size (~400,000 vs ~3,500), minimum engagement (Not disclosed vs Not disclosed), and primary industries served (Financial services, Insurance vs Energy & utilities, Banking).
Verify all details directly with each firm before making a decision.