Aon plc (AON) Operational Quality Rating (AA)

(AA) | Financials | Insurance Brokerage & Consulting
By: Old York Financial
A Private Principal Report

the verdict

Old York Financial has assigned Aon plc (AON) an Operational Quality (AA) Rating. Aon is the mirror image of Marsh, a capital-light toll bridge that dominates the movement of global risk. However, Aon is currently the "More Aggressive Twin." While Marsh focuses on 18 years of steady margin expansion, Aon has spent the last two years digesting the massive $13 Billion NFP acquisition, which has temporarily bloated its balance sheet and suppressed its raw ROIC.

Aon earns its (AA) because it possesses a structural monopoly in Risk and Human Capital consulting. It is an "Asset-Light" cash machine that converts nearly 19% of its revenue into Free Cash Flow. It falls short of (AAA) due to the same "Goodwill Bloat" as Marsh and a significantly higher debt-to-capital ratio (60.9%) following its recent M&A spree.

the old york analysis

owner earnings: the high-flow engine

Aon is a master of cash conversion. In 2025, they proved that even while integrating a massive acquisition, the "Aon United" model prints money.

• 2025 Net Cash from Operations: $3.48 Billion

• (-) Maintenance CapEx (Tech/ABS Platform): ($0.26 Billion)

• (+) Amortization of Intangibles: $0.74 Billion

• OLD YORK OWNER EARNINGS: $3.96 Billion

Analyst Note: Aon’s maintenance CapEx is remarkably low at ~1.5% of revenue. This is the "Asset Light" dream. They don't build factories; they build "Aon Business Services" (ABS) platforms that scale globally with zero incremental cost.

growth & market dominance

• Monopoly Characteristics: Aon and Marsh are the only two players capable of handling the complexity of a global Fortune 100 account. This is a high-barrier-to-entry duopoly.

• The NFP Integration: The 2025 results show Aon is successfully moving into the "Middle Market" via NFP, capturing a segment previously held by smaller, less efficient brokers.

operational efficiency (yardstick v4)

• ROIC: 8.18% (Stated TTM) / ~15.7% (Adjusted Core).

  • Forensic Note: On an unadjusted basis, Aon fails the 15% hurdle. However, their Core Return on Capital (excluding the NFP acquisition's massive goodwill) is north of 15.7%. For the Registry, we acknowledge the quality, but the "Bloat" keeps them out of the AAA tier.

• Net Profit Margin: 21.5%.

• Operating Margin: 25.3% (Stated) / 32.4% (Adjusted).

• EPS Growth: 36% (Stated 2025) / 9% (Adjusted CAGR).

Analyst Note: The 138% jump in Q4 2025 EPS was "flattered" by the sale of NFP Wealth. We look past the headline to the 9% adjusted growth.

the fortress check

• The Reduction Factor: CONSISTENT.

  • 2025 Buybacks: $1.0 Billion.

  • Net Dilution: Zero over the long term, though they issued 19M shares in 2024 for the NFP deal. They have already resumed the "Cannibal" behavior, shrinking the float by 0.7M shares in Q4 2025 alone.

• The Debt Warning: Long-term debt stands at $14.7 Billion. Their debt-to-capital is 60.9%, which is high. They paid down $1.9B in 2025 to fix this, showing the "Buffett-style" discipline you look for.

why it’s rated (AA)

• The "Twin" Discount: Like Marsh, Aon’s balance sheet is "heavy" with the ghosts of past acquisitions (Goodwill). This suppresses the pure ROIC below the 15% Yardstick floor.

• Execution Risk: Aon is currently in the middle of its "3x3 Plan" and "Accelerating Aon United" restructuring. Until the integration of NFP is fully "clean," they remain a tier below the Sovereigns.

• Asset Light Excellence: They are fundamentally better businesses than the insurers they serve (Allstate/Travelers) because they have zero catastrophe risk.

final determination

Rating: Old York Quality (AA)

Classification: The Transactional Sovereign.

Aon is a "Buy and Forget" quality business. It’s a (AA) because it provides essential services that companies cannot function without, backed by a massive share-retirement engine. It’s the "Brokers' Broker."

Disclaimer: Old York Financial operates privately as a principal and sells corporate advisory. Old York Financial is not an accountant, a financial advisor, a broker, an agent, a lawyer, or a portfolio manager.