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Aon vs Marsh McLennan Agency

Aon lists management liability, umbrella and excess liability; Marsh McLennan Agency lists intellectual property, media. Their published catalogs also share 14 lines, including builders risk, cargo transit, commercial auto. Use the differences to frame the same quote request for both, then confirm the producer, insurer, and policy terms; a listed product does not establish availability or equivalent coverage. 1,4,29,16,6,21

Introduction

Coverage Comparison

CoverageAonMarsh McLennan Agency
Builders riskListed 14Aon names Construction Property/Builders Risk on its global construction page; confirm whether this line is offered for the buyer, state, and placement.Listed 26
Cargo and transitListed 9Aon lists cargo placements in its global marine practice; U.S. eligibility, insurer, limits and policy terms are not stated on the reviewed page.Listed 23
Commercial autoListed 6Aon lists automobile liability within its global Professional Services Practice for law, accounting and consulting firms; U.S. availability and specific policy terms are not established.Listed 29
Commercial propertyListed 8Aon describes commercial-property brokerage and risk management, with a U.S.-available analytics tool; tool availability does not establish state-specific insurance availability.Listed 29
CrimeListed 6Aon lists crime within its global Professional Services Practice for law, accounting and consulting firms; U.S. availability and specific policy terms are not established.Listed 21
Cyber liabilityListed 7,6Aon describes cyber insurance and related brokerage, analytics and claims support; confirm the producing entity, insurer, jurisdiction and policy terms for a U.S. placement.Listed 29
Directors and officersListed 5Aon describes D&O brokerage and program services in a global practice; this does not identify the producer, insurer or state availability for a particular U.S. placement.Listed 21
Employment practices liabilityListed 6Aon lists EPL for professional-services firms in a global practice; this does not establish eligibility for every U.S. employer or state.Listed 21
Fiduciary liabilityListed 6Aon lists fiduciary liability within its global Professional Services Practice for law, accounting and consulting firms; U.S. availability and specific policy terms are not established.Listed 21
General liabilityListed 14Aon lists general liability within construction liability coverage areas in its global construction practice; this does not establish a standalone or U.S.-available line.Listed 29
Intellectual propertyNot listedListed 21
Kidnap and ransomListed 6Aon lists kidnap and ransom within its global Professional Services Practice for law, accounting and consulting firms; U.S. availability and specific policy terms are not established.Listed 21
Management liabilityListed 6Aon describes management liability in its global Professional Services Practice as a partnership program for law, accounting and consulting firms, rather than a standalone line; U.S. availability and specific policy terms are not established.Not listed
Media liabilityNot listedListed 21
Professional errors and omissions (E&O)Listed 6Aon describes professional-liability/E&O services for law, accounting and consulting firms; a U.S. placement and any separate technology E&O terms remain to be confirmed.Listed 29
Surety bondsListed 10Aon markets Commercial Surety globally and says availability depends on jurisdiction; the page does not establish U.S. placement availability.Listed 30
Umbrella and excess liabilityListed 14Aon lists umbrella and excess within construction liability coverage areas; ask whether either applies to your project and jurisdiction.Not listed
Workers’ compensationListed 14Aon lists workers compensation among global construction coverage areas; this does not establish state availability or a placement.Listed 29

A listing may be arranged through an insurer or partner. “Not listed” means this catalogue has no separate offering recorded; ask the provider whether it can quote the coverage and request the policy terms.

Current Spot Scores

Each score uses the rubric for that provider’s documented role. Providers with more than one role may have a score for each.

Aon

Broker

Broker

6.7/ 10

Assessed provider: Aon. Scope: Aon group commercial insurance brokerage, assessed at brand level from Aon's published terms, its 2025 SEC filing, and U.S., U.K. and Irish regulator records. It does not assess a single producing entity, insurer or placement, and it is not a ruling on Aon's consulting or benefits businesses.

Provider assessment

Marsh McLennan Agency

Broker

Broker

No Spot Score

Assessment subject unavailable

Provider assessment

Review Scores

These averages can combine ratings for different products, locations, and customer groups, including approximate BBB grade conversions. Read each review for the sources, scope, and calculation.

Aon

6.1/ 10

Review Score

3 rated sources

Public ratings for Aon are low: Trustpilot shows 1.2 out of 5 from 782 reviews, and BBB shows 1.6 from five. Aon is a global firm, so those pages mostly reflect other parts of the business, not large U.S. commercial accounts.[4][6][7]

Read Aon reviews

Marsh McLennan Agency

8.2/ 10

Review Score

2 rated sources

There are almost no public customer reviews of Marsh McLennan Agency (MMA). Trustpilot shows 3.2 out of 5, but from a single review, and BBB shows an A grade with four complaints closed in three years.[8][9][1]

Read Marsh McLennan Agency reviews

Where the Buying Paths Differ

Aon describes its route this way: For certain U.S. Commercial Risk programs, Aon says it consults with the client about market conditions, insurers to approach and program strategy, helps prepare underwriting information and applications, and obtains the client’s instructions to bind specific programs based on Aon’s proposal. The client signs applications that require a signature. 1 Marsh McLennan Agency describes its route this way: MMA lists general liability, commercial property, workers’ compensation, professional liability, commercial auto, and cyber liability for small businesses, and invites buyers to call for a personalized quote. It does not describe an online purchase or binding route. 29 The useful distinction is where the first submission goes and who continues with the account. Ask who gathers information, who can bind, which legal producer appears on the proposal, and who remains your day-to-day contact; a quote request alone does not establish an issued policy.

Customer Fit and Published Product Menus

Aon lists its business focus as Aon markets a dedicated Middle Market practice for mid-sized organizations and says it serves growing businesses across North America; the reviewed page states no numerical size cutoff or U.S.-only eligibility rule. 4 Marsh McLennan Agency lists its business focus as Business insurance and employee health and benefits, with retirement, wealth, and private-client services also listed for the United States and Canada. 16 Match those stated audiences to your operations, locations, contracts, and loss history, then ask which practice or team would service the account. A stated focus is not an eligibility decision.

The published catalogs list Aon lines not listed by Marsh McLennan Agency: management liability, umbrella and excess liability; Marsh McLennan Agency lines not listed by Aon: intellectual property, media. These differences do not establish that either company excludes a line or will quote your risk. 6 14 21 26

Both providers list builders risk, cargo transit, commercial auto, commercial property, crime, cyber, directors and officers, employment practices, fiduciary, general liability, kidnap ransom, professional E&O, surety bonds, workers’ compensation. Treat that overlap as a shortlist for a side-by-side proposal review, not proof of matching policy language. For each line, compare the named insurer, insured entities, limits, deductibles or retentions, exclusions, endorsements, retroactive dates where relevant, and state-specific terms. 14 9 26 23

Service and Quote Questions

For Aon, published service information says: Aon says it consults with clients before placing or renewing coverage and, where applicable, administers the insurer relationship for selected programs, including billing, data reporting and negotiated requirements. The terms do not promise automatic renewal, a timetable, a specific market or a particular outcome. 1 For Marsh McLennan Agency, it says: MMA says the Marsh Agency brand transition will not change clients’ account manager, team, or point of contact, and will not affect existing policies or programs; clients may see the legal-name change during renewals. This describes the rebrand transition, not MMA’s general renewal process. 27 Before binding, agree on routine endorsement requests, certificates, renewal timing, claim-notice instructions, and any fee or commission disclosure that applies to your account. Claims assistance or a service portal does not determine whether a loss is covered.

For a useful quote comparison, request the same limits and relevant endorsements from both sides, then check the full forms and itemized premium, fees, taxes, and financing charges. Confirm any account-specific unknowns with the producer and insurer named on the proposal.

Compare Services

What each provider documents about the services you may need

CriteriaAonMarsh McLennan Agency
Business role

Aon’s U.S. Commercial Risk terms describe Commercial Risk Solutions U.S. as broker of record for certain insurance programs. Separate electronic-delivery terms name Aon Risk Services Companies, Inc. acting for itself and licensed brokerage subsidiaries to deliver arranged policies; the terms define an insurer as the policy issuer and risk bearer. These group-level descriptions do not identify the producer or authority for a particular placement. 1,2Company-reported. Company-reported U.S. Commercial Risk brokerage and electronic-delivery terms; certain programs only. No specific insured, licensed producer, appointment, policy issuer, state authority or placement was matched.

As of 2026-09-28, Marsh’s US legal-entity page lists Marsh & McLennan Agency LLC as the current entity name for Marsh Agency (formerly MMA) and Marsh Agency LLC as proposed, with displayed state completion statuses marked TBD. Louisiana’s regulator lists Marsh & McLennan Agency LLC as a producer agency with active casualty, accident and health or sickness, life, property, and surplus-lines authorities through 2028-03-31. This is Louisiana-specific producer evidence, not evidence of an insurer role or nationwide licensing. 24,15Verified. Current entity name and proposed legal-name transition as listed on Marsh’s US legal-entity page, plus producer-authority evidence for Louisiana only, accessed 2026-09-28. No other state licensing was audited; this record does not establish an insurer or underwriting role.

Marsh McLennan Agency describes itself as a business of Marsh and lists business insurance, employee health and benefits, retirement and wealth, and private-client insurance services across the United States and Canada. 16Company-reported. Current MMA company description. Does not establish corporate ownership structure, the legal entity for a particular placement, or an insurer role.

Customer focus

Aon markets a dedicated Middle Market practice for mid-sized organizations and says it serves growing businesses across North America. The reviewed page gives no numerical size cutoff and does not establish U.S.-only eligibility; Aon’s broader global client statement describes the parent’s client base, not this practice’s eligibility rules. 4,3Company-reported. Company-reported marketing page, North America; no numerical revenue, employee-count, state or U.S.-only eligibility definition is stated.

MMA describes Marsh Agency as a separate business unit serving as an advocate and broker for the middle market. 27Company-reported. Company-stated role and customer focus for the future Marsh Agency operating brand; not a revenue, size, or eligibility threshold.

MMA’s US industry directory includes pages for construction, financial institutions, healthcare, manufacturing, real estate, and transportation and trucking. These are examples of stated sector focus, not a complete appetite or eligibility list. 22Company-reported. Examples from MMA’s national US industry directory; the directory is evidence of stated sector focus, not a complete appetite or eligibility list.

Application process

For certain U.S. Commercial Risk programs, Aon says it consults with the client about market conditions, insurers to approach and program strategy, helps prepare underwriting information and applications, and obtains the client’s instructions to bind specific programs based on Aon’s proposal. The client signs applications that require a signature. 1Company-reported. Company-reported contractual terms for certain U.S. Commercial Risk programs; not a universal workflow, online checkout claim, insurer role or guarantee that a quote can bind.

MMA’s US small-business page lists general liability, commercial property, workers’ compensation, professional liability, commercial auto, and cyber liability, and invites buyers to call 833-256-4266 for a personalized quote. The page also contains a small-business specialist form, but its function and any online application, purchase, or binding route are not established by the page reviewed. 29Company-reported. US small-business landing page only. The phone invitation does not establish quote speed, eligibility, online purchase or binding; the embedded specialist form's function was not established.

Servicing and renewals

Aon says it consults with clients before placing or renewing coverage and, where applicable, administers the insurer relationship for selected programs, including billing, data reporting and negotiated requirements. The terms do not promise automatic renewal, a timetable, a specific market or a particular outcome. 1Company-reported. Company-reported terms for selected U.S. Commercial Risk programs; administration varies where applicable and may be changed by written agreement.

MMA says the Marsh Agency brand transition will not change clients’ account manager, team, or point of contact, and will not affect existing policies or programs; clients may see the legal-name change during renewals. This describes the rebrand transition, not MMA’s general renewal process. 27Company-reported. Only the announced Marsh Agency rebrand and its stated effect on existing clients; this does not document MMA’s general renewal workflow, renewal service level, or policy terms.

MMA’s Tampa office page lists InsurLink for policy and endorsement access, CSR24 for certificates, carrier contact information for commercial and personal-lines claims, and a local-consultant contact route. 31Company-reported. Services and client tools listed on the Tampa, Florida office page only. The claims listing provides carrier contact information and does not establish that MMA adjusts claims.

Claims assistance

Under Aon’s U.S. brokerage terms, the client is responsible for directly notifying insurers as its policies require unless a separate signed agreement says otherwise; Aon says it does not assume that notice or monitoring duty without a separate written agreement. This allocation does not determine whether Aon separately offers or agrees to claims advocacy or other claims-related services. 1,5,7Company-reported. Company-reported contractual allocation for covered U.S. Commercial Risk services; policy terms and any separate written agreement control. Aon separately describes claims advocacy on its D&O and cyber pages.

On its business-interruption page, MMA says it will advocate with insurers for clients if complex claim issues arise. This is a company-reported service statement; it does not establish claim outcomes or an adjusting/payment role. 17Company-reported. Company-described support for complex claims in the business-income and contingent-business-interruption page context; not a promise of claim outcomes or evidence that MMA adjusts or pays claims.

Sources

Aon Official Website

  1. Commercial Risk Solutions U.S. Brokerage Terms of Service. Aon; Lines 120–127: certain-program broker-of-record scope, consultation, application assistance, client signature and bind instruction, and account administration; lines 140–147: variable and contingent compensation, potential placement incentive, and client request route; lines 206–213: no price guarantee and surplus-lines limitations; lines 229–231: client insurer-notice duty unless separately agreed. Accessed 2026-09-29.
  2. Aon Commercial Risk U.S. Electronic Disclosure and Consent Terms. Aon; Lines 120–125: Aon Risk Services Companies, Inc. acting for itself and licensed brokerage subsidiaries in electronic delivery; insurer is defined as issuer and risk bearer. The passage does not identify a producing entity or insurer for a particular placement. Accessed 2026-09-28.
  3. Aon plc Form 10-K for the year ended December 31, 2025. Aon plc / U.S. Securities and Exchange Commission; Cover lines 23–34: Aon plc is incorporated in Ireland and gives Dublin as principal executive office; lines 261–263: global client breadth; lines 271–273 and segment discussion: company-reported Commercial Risk brokerage and risk-consulting operations. Filing is parent-level evidence, not placement producer, authority or insurer evidence. Accessed 2026-09-29.
  4. Middle Market Clients. Aon; Lines 125–132: mid-sized organizations and middle-market framing; lines 165–173: dedicated practice and North America statement; lines 188–224: Commercial Risk capabilities. No numeric company-size cutoff or U.S.-only eligibility rule is stated on the reviewed page. Accessed 2026-09-29.
  5. Directors’ and Officers’ (D&O) Liability Insurance. Aon; Lines 135–160: general covered allegations and Side A, B and C scenarios, including public/private differences; lines 171–185: insurer-selection analytics, brokerage/claims-team collaboration and management-liability specialization. Product explanation and company-reported services; not an Aon-issued policy or quote. Accessed 2026-09-29.
  6. Professional Services Practice | Insurance Broking & Risk Management. Aon; Lines 125–128: global professional-services team and named law, accounting and consulting firm audience; lines 131–147: professional-liability/E&O offering and terminology; lines 151–176: cyber and EPL offerings, including management liability described at lines 158–163 as a partnership program/category; lines 180–189: professional-services P&C listing, including crime, fiduciary, kidnap and ransom, and automobile liability. “Loss Prevention” section (directly inspected passage at lines 209–212) conditions law-firm loss prevention on Aon broking of lawyers’ professional liability. Global practice page; no state-specific placement schedule. Accessed 2026-09-29.
  7. Cyber Risk. Aon; Lines 194–205: cyber risk financing and cyber insurance; lines 206–230: claims advocacy/preparation and third-party incident-response providers, separate client contracts, no performance guarantee, and possible referral remuneration. Company-reported global service description. Accessed 2026-09-29.
  8. Property Risk Management. Aon; Lines 132–140: property/buildings/contents and possible business-interruption cover, broker team services; lines 148–159: rates, retentions, limits, deductibles, benchmarking and U.S.-available Property Risk Analyzer; lines 161–168: global market access and alternate risk transfer. Tool availability does not establish placement availability or authority by state. Accessed 2026-09-29.
  9. Marine Insurance and Risk Management. Aon; Lines 123–126: global marine practice, customer examples and marine claims/risk services; lines 155–175: cargo offerings including project cargo, general cargo, stock throughput, excess storage and freight/logistics. No U.S. placement terms, insurer, limits or state authority specified. Accessed 2026-09-29.
  10. Commercial Surety. Aon; Lines 125–127: commercial surety bond description and three parties; lines 190–210: Aon says it approaches the surety market globally and describes its brokerage support, with offerings depending on jurisdiction; lines 211–222: examples of bond types. Global company marketing; no U.S. producing entity, state authority, issuer or placement terms. Accessed 2026-09-29.
  11. About | Aon. Aon; Aon’s company overview and Our Capabilities list distinguish Risk Capital from Human Capital and describe group-wide capabilities. General company identity context; not placement, authority or insurer evidence. Accessed 2026-09-28.
  12. Broking and Risk Transfer | Aon. Aon; Explore Our Risk Transfer Offerings; Property & Casualty, Specialty, Management Liability and industry listings. Broad catalogue only; not sufficient for a dedicated line record by itself. Accessed 2026-09-28.
  13. Financial and Executive Risks | Insurance Broking & Risk Management. Aon; Financial Services Group Overview; D&O, fiduciary, EPL and crime references plus policy design and insurer market knowledge. Broad category/source context; not sufficient by itself to establish a separate U.S. product. Accessed 2026-09-28.
  14. Construction and Infrastructure Insurance and Risk Management. Aon; Lines 125–126: global construction practice designing and placing risk solutions; lines 137–156: industry-specific property, casualty, construction professional liability, subcontractor default and construction surety offerings; lines 167–195: global coverage areas explicitly list Builders Risk, general/umbrella/excess liability within construction liability, workers compensation and surety among other categories. These are construction-practice marketing statements; page does not provide U.S. state or placement availability for each line. Accessed 2026-09-29.

Marsh McLennan Agency Official Website

  1. Producer / Adjuster Search: MARSH & MCLENNAN AGENCY LLC. Louisiana Department of Insurance; Producer Agency Detail, lines 7-49: entity, producer-agency classification, license number, authorities and validity through 2028-03-31; lines 53-57: historical 2010 lapse/resume entries; lines 69-72: entity-record actions display. Accessed 2026-09-28.
  2. Who We Are. Marsh McLennan Agency; Lines 193-195: ‘a business of Marsh’ and company-listed service lines across US and Canada. This does not establish the legal entity for an account, corporate ownership chart, or insurer role. Accessed 2026-09-29.
  3. Business Interruption Insurance. Marsh McLennan Agency; Accepted inspection lines 224-226: company says it will advocate with insurers on complex claim issues. No outcomes, adjustment/payment role, or insurer identity established. Accessed 2026-09-28.
  4. Casualty. Marsh McLennan Agency; Lines 203-205 and 211-224: casualty advisory, claims advocacy, risk analytics and workers’ compensation. No adjusting or paying role established. Accessed 2026-09-29.
  5. Cyber. Marsh McLennan Agency; Lines 205-207: network security, privacy, technology and emerging cyber risks; lines 226-228: prepare, mitigate, respond, recover, claims advocacy and carrier liaison. Company-reported support, not outcomes or insurer identity. Accessed 2026-09-29.
  6. US and Canada Legal Entities. Marsh; Accepted inspection lines 528-587: current MMA entity Marsh & McLennan Agency LLC; Marsh Agency LLC proposed; displayed state statuses TBD. Accessed 2026-09-28.
  7. Executive and Professional Liability. Marsh McLennan Agency; Lines 204-210 name D&O, E&O, EPL, commercial crime/fidelity, cyber, fiduciary, media, IP, architects and engineers, lawyers professional, kidnap and ransom; lines 211-213 explain D&O; following section explains EPL. Lists do not establish policy terms. Accessed 2026-09-29.
  8. Insurance Services for All Industries. Marsh McLennan Agency; National US industry directory, lines 209-252; examples include construction (219), financial institutions (224), healthcare (229), manufacturing (236), real estate (243), and transportation and trucking (252). Accessed 2026-09-28.
  9. International. Marsh McLennan Agency; Lines 204-206 and 228-231: international placement; business travel accident, control master, foreign package, K&R, political risk/trade credit, surety, marine cargo. Not a domestic availability guarantee. Accessed 2026-09-29.
  10. Marsh legal entities. Marsh; Marsh Agency formerly known as MMA, US entities and proposed-name status, lines 528-587: current Marsh & McLennan Agency LLC, proposed Marsh Agency LLC, listed state statuses TBD. Accessed 2026-09-28.
  11. Producer/Adjuster Search — producer agency detail. Louisiana Department of Insurance; Accepted inspection lines 7-49 and 53-57: Marsh & McLennan Agency LLC producer agency and named Louisiana authorities through 2028-03-31, including historical lapse/resume entries. Louisiana only; distinct from Marsh USA LLC/NPN 27658. Accessed 2026-09-28.
  12. Property Insurance. Marsh McLennan Agency; Lines 205-210 describe commercial property and physical assets; property page coverage section also lists builders’ risk. Company marketing only; no policy wording, limits, exclusions, insurer, or eligibility. Accessed 2026-09-29.
  13. Rebranding to Marsh Agency. Marsh McLennan Agency; Accepted repaired inspection lines 215-224: account/team/contact and existing policy continuity through transition, legal name may appear at renewal. Transition statement only; not general renewal workflow. Accessed 2026-09-29.
  14. Business Insurance. Marsh McLennan Agency; ‘We do our homework’: research of organization, industry, market and people; says it works with a wide variety of carriers. No carrier appointments, shares, terms, compensation, or buyer-specific insurer named. Accessed 2026-09-29.
  15. Small Business Insurance Solutions. Marsh McLennan Agency; Lines 205-207: small-business audience and call invitation; lines 224-249 list six coverage categories and short descriptions; line 264 is an embedded form whose function is not stated. No form submitted. Accessed 2026-09-29.
  16. Surety. Marsh McLennan Agency; Lines 205-207 and 224-233: surety, contract/commercial surety, and license/permit bonds. No surety carrier, collateral, price, or issuance time established. Accessed 2026-09-29.
  17. Tampa, Florida. Marsh McLennan Agency; Accepted repaired inspection lines 252-289: InsurLink policy/endorsement access, CSR24 certificates, carrier contacts for claims, consultant contact. Tampa only; does not establish adjusting role. Accessed 2026-09-29.
  18. Thompkins Masonic Insurance Program. Marsh McLennan Agency / MMA Programs; Provider page, lines 120–127: body says “Thompkins Masonic Insurance Program, a Marsh & McLennan Insurance Agency LLC company, is licensed under California License #OH18131”; line 127 says MMA Programs is a division of Marsh & McLennan Agency LLC. Page footer, line 161, instead prints “d/b/a in California as Marsh & McLennan Insurance Agency LLC; CA Insurance Lic: 0H18131.” The page itself therefore renders the identifier in two different ways. Accessed 2026-09-29.

Updated . Spot, a product of Tools for Enlightenment, publishes this research and works in the commercial insurance market. Editorial policy. To suggest a correction, contact Spot with the page URL and supporting source.

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