Aon vs Marsh: Professional Liability / E&O Insurance

Marsh's practice places professional liability, with attorneys, economists and actuaries alongside coverage specialists assessing exposure for banks, asset managers and venture capital; Aon's practice is aimed at law, accounting and consulting firms.

Kearny Risk organizes these comparisons for firms whose advice, content or technology creates professional exposures.Research updated 2026-09-30

Areas of coverage

Aon

  • role: Aon presents Professional Liability / E&O as a line its Professional Services Practice helps arrange or advise on for professional-service firms. Aon is describing a global brokerage and advisory service, not issuing the underlying policy. The producing legal entity and carrier for any particular placement are not named on this page. Aon’s global professional-services practice page. This establishes a marketed brokerage/advisory offering, not policy issuance or account-specific placement.company-reportedSource ↗
  • eligibility: Aon identifies law, accounting and consulting firms as the audience for its global Professional Services Practice. That audience scope does not establish eligibility for every firm or other business. Audience described for Aon’s global professional-services practice. It does not establish U.S. state availability or underwriting eligibility for a placement.company-reportedSource ↗
  • coverage: Aon describes professional liability as addressing professional-services firms’ liability exposure and says it tailors coverage structures to a firm’s needs. It identifies E&O as a commonly used name for professional-liability insurance; actual policy terms are not stated. Aon’s marketing description of the brokerage/coverage area. The page is not the insurer’s policy form and does not establish an insured's entitlement to coverage.company-reportedSource ↗
  • services: Aon says its professional-services advisors use industry knowledge, insights, data and tools to support risk-management and human-capital decisions. This is a company-described advisory service, not a claim outcome or policy benefit. Company-reported advisory services on Aon’s global practice page; account-specific service scope is not stated.company-reportedSource ↗
  • insurer: The reviewed practice page does not name the insurer or producing legal entity for a specific placement. Ask for both on the quote and binder. Aon’s global practice page as reviewed 2026-09-30; no state-specific placement schedule or buyer quote was reviewed. This does not establish that Aon cannot arrange a placement.not-foundSource ↗
  • limits: The reviewed page does not state a buyer-specific limit, retention, deductible or other placement terms. Confirm these in the quote, bond or issued policy. Aon’s global practice page as reviewed 2026-09-30; no quote, bond form or issued policy was reviewed.not-disclosedSource ↗

Marsh

  • role: Marsh's financial and professional liability practice places professional liability (errors and omissions) insurance; MMA also places E&O coverage within its executive and professional liability practice for middle-market clients. Marsh professional liability page and MMA executive and professional liability page.company-reportedSource ↗Source ↗
  • coverage: Marsh says professional liability coverage can protect a company against liability and defense costs from a claim alleging an error, omission or negligence in performing professional services, and that many policies also cover privacy violations and computer security breaches. Marsh professional liability page opening description; illustrative policy description, not a specific policy form.company-reportedSource ↗
  • eligibility: Marsh names specialized industries its professional liability experts serve, including banking and broker/dealers, insurance companies and asset managers, merchant banking and venture capital, accountants, attorneys, architects and engineers, media and entertainment, technology, and healthcare and biotechnology. Marsh professional liability page, What We Offer section.company-reportedSource ↗
  • insurer: The reviewed pages do not name a specific professional liability insurer. Marsh professional liability page and MMA executive and professional liability page as read on 2026-09-23.not-disclosedSource ↗Source ↗
  • services: Marsh says it employs attorneys, economists and actuaries alongside coverage specialists to assess a client's professional liability exposure from multiple angles, given the complexity of these risks. Marsh professional liability page.company-reportedSource ↗

What Are the Key Differences Between Aon and Marsh Professional Liability (E&O) Insurance?

Professional Class and Product Scope

Aon says it tailors professional-liability structures for professional-services firms, but does not list coverage features on its practice overview. Marsh says E&O can respond to liability and defense costs for alleged errors, omissions or negligence in professional services; it adds that many policies also cover privacy violations and computer-security breaches. A buyer with blended professional and technology exposure should ask whether those extensions are actually in the Marsh form and compare them with Aon’s proposed wording. [1] [4]

Placement Detail and Buyer Decisions

Marsh names specialized fields including banking, venture capital, accounting, law, architecture, media, technology and healthcare, and says it uses attorneys, economists and actuaries alongside coverage specialists to assess exposures. Aon’s listed audience is law, accounting and consulting firms, with advisors using data and industry knowledge. Neither record names the carrier or publishes limits. Confirm the insurer, insured services definition and any cyber sublimit before treating the descriptions as comparable. [1] [4]

What Should You Confirm in Aon and Marsh Professional Liability (E&O) Insurance Quotes?

  • Ask Marsh whether privacy and computer-security claims are included, excluded or sublimited on the quote. [1] [4]
  • Ask Aon which carrier, professional-services definition and limits apply to your specific industry. [1] [4]

Aon describes tailored professional-liability structures without form details. Marsh says E&O can cover liability and defense costs for alleged service errors and that many policies also cover privacy or computer-security claims.

Sources reviewed

  1. 01
    Professional Services Practice

    Aon · Named professional-services audiences and global advisory role, lines 125–128; line offerings and explanations lines 131–190; contact link lines 120–122. Global practice page; no U.S. state or account-specific placement schedule. · accessed 2026-09-30

  2. 02
    Professional Liability – US Direct Errors and Omissions Insurance

    Hiscox Inc. specimen · About this Policy / Coverage for Claims Made Against You; I.A Insuring Agreement; I.B Defense; I.C Settlement; II.A Notice of Claims; II.C Optional Extended Reporting Period; III.A, III.K, III.M, III.R, III.S Exclusions; IV.A–B Limits and Deductible; VI.O Professional Services; VI.U Wrongful Act · accessed 2026-09-16

  3. 03
    Professional liability insurance

    Insurance Information Institute · Opening paragraphs (professional services/advice and E&O name); Claims not covered by general liability; What types of businesses need professional liability insurance?; What’s covered… and what’s not (claims-made versus occurrence, defense and judgments, non-financial/intentional limits, BOP/in-home exclusion) · accessed 2026-09-16

  4. 04
    Professional liability

    Marsh · Opening description; What We Offer: specialized industries served (banking, insurance/asset managers, merchant banking/venture capital, accountants/attorneys/architects/engineers, media/communications/entertainment, technology, healthcare/biotechnology) · accessed 2026-09-23

  5. 05
    Expert Executive and Professional Liability Insurance

    Marsh McLennan Agency · Our policies include D&O, E&O, EPL, commercial crime/fidelity, network security privacy risk/cyber, fiduciary, media liability, IP, architects and engineers, lawyers professional, and kidnap and ransom · accessed 2026-09-23

  6. 06
    FAQ: Professional liability insurance

    Texas Department of Insurance · What’s professional liability coverage?; What types of damages…; What’s general liability insurance?; Do I need professional liability… if I have general liability…?; Is professional liability insurance required?; Can a client require…?; What’s the difference between occurrence policies and claims-made policies · accessed 2026-09-16

  7. 07
    Get business insurance

    U.S. Small Business Administration · Six common types of business insurance table · accessed 2026-09-16

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