Comparable stake leader
MASSACHUSETTS FINANCIAL SERVICES CO /MA/
SEC ownership of Aon plc
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000315293.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
12 May 2026
- Public ticker
- AON on NYSE
- Parsed ownership sources
- 13D/G, 13F, and 3/4/5
- Largest SEC-reported holder
- MASSACHUSETTS FINANCIAL SERVICES CO /MA/
- Latest 13D/G holder
- MASSACHUSETTS FINANCIAL SERVICES CO /MA/
- Latest parsed ownership date
- 12 May 2026
- Issuer CIK
- 0000315293
- Issuer location
- Dublin 2, Ireland
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Aon plc (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
MASSACHUSETTS FINANCIAL S...
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
12 May 2026
13D/G
13F
3/4/5
Lead comparable stake: 4.6%
13D/G row: MASSACHUSETTS FINANCIAL SERVICES CO /MA/
Showing 1-8 of 50 holder rows.
Quick read
MASSACHUSETTS FINANCIAL SERVICES CO /MA/ leads the comparable SEC ownership view at 4.6%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens MASSACHUSETTS FINANCIAL SERVICES CO /MA/'s linked filing trail.
Comparable ownership
Top 5
MASSACHUSETTS FINANCIAL SERVICES ...
4.6%
Gregory C. Case
0.52%
Lester B. Knight
0.14%
Gloria Santona
0.02%
Cheryl A. Francis
0.01%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| MASSACHUSETTS FINANCIAL SERVICES CO /MA/ |
13D/G
13F
Massachusetts Financial Services Company · Company
|
4.6%
|
$3,302,227,997
9,832,449 shares
|
$0 | 31 Mar 2025 |
| Gregory C. Case |
3/4/5
President & CEO, Director
|
0.52%
|
$381,298,753
1,108,878 shares
|
— | 19 Feb 2026 |
| Lester B. Knight |
3/4/5
Director
|
0.14%
|
$98,798,215
297,376 shares
|
+$1,276,956 | 10 Feb 2026 |
| Gloria Santona |
3/4/5
Director
|
0.02%
|
$14,123,409
39,608 shares
|
— | 12 Nov 2025 |
| Cheryl A. Francis |
3/4/5
Director
|
0.01%
|
$10,148,288
28,704 shares
|
— | 26 Jun 2025 |
| NOTEBAERT RICHARD C |
3/4/5
Director
|
0.01%
|
$8,953,261
27,738 shares
|
— | 12 May 2026 |
| Jeffrey C. Campbell |
3/4/5
Director
|
0.01%
|
$4,253,549
12,031 shares
|
— | 26 Jun 2025 |
| Jin-Yong Cai |
3/4/5
Director
|
0%
|
$2,639,383
7,465 shares
|
— | 26 Jun 2025 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$4,814,627.
Buys
$1,276,956
Insiders: 1
Sells
$6,091,584
Insiders: 1
Net
-$4,814,627
Shares: -14,140
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 4,000
Shares: 18,140
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 4,000 | 9,340 | $1,276,956 | $3,059,765 | -$1,782,809 |
| 6-9 | 0 | 8,800 | $0 | $3,031,818 | -$3,031,818 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 31 reporting-owner rows connected to Aon plc. Open a relationship link for the CIK-to-CIK filing trail.
Rows
31
Largest Forms 3/4/5 holder
Gregory C. Case
Net 12M change
-$4,814,628
Latest report
12 May 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Gregory C. Case | President & CEO, Director | $381,298,753 | Mixed | 19 Feb 2026 | ||
| Eric Andersen | President | $119,059,242 | Mixed | 13 Feb 2025 | ||
| Lester B. Knight | Director | $98,798,215 | +$1,276,956 | +1.3% | Mixed | 10 Feb 2026 |
| Christa Davies | Chief Financial Officer | $50,329,363 | Mixed | 15 Feb 2024 | ||
| Gloria Santona | Director | $14,123,409 | Mixed | 12 Nov 2025 | ||
| Andy Weitz | Chief Marketing Officer | $12,923,829 | Mixed | 15 Feb 2024 | ||
| Cheryl A. Francis | Director | $10,148,288 | Mixed | 26 Jun 2025 | ||
| Fulvio Conti | Director | $9,153,269 | Mixed | 20 Jun 2024 | ||
| Richard B. Myers | Director | $9,105,655 | Mixed | 25 Jun 2021 | ||
| Lisa Stevens | Chief Administrative Officer | $9,050,907 | Mixed | 18 Feb 2026 | ||
| Carolyn Y. Woo | Director | $8,993,557 | Mixed | 15 Jun 2023 | ||
| NOTEBAERT RICHARD C | Director | $8,953,261 | Median | 12 May 2026 | ||
| J. Michael Losh | Director | $8,763,426 | Mixed | 17 Jun 2022 | ||
| Darren Zeidel | General Counsel | $5,260,339 | -$6,091,584 | -54% | Filing P/S | 26 Feb 2026 |
| Michael Neller | Principal Accounting Officer | $4,324,834 | Mixed | 14 Mar 2025 | ||
| Jeffrey C. Campbell | Director | $4,253,549 | Mixed | 26 Jun 2025 | ||
| Andy Marcell | Global CEO, Solution Lines | $2,848,544 | Mixed | 13 Mar 2026 | ||
| Jin-Yong Cai | Director | $2,639,383 | Mixed | 26 Jun 2025 | ||
| Lori Goltermann | CEO, Regions & North America | $2,194,793 | Mixed | 13 Mar 2026 | ||
| Mindy F. Simon | Chief Operating Officer | $2,089,919 | Mixed | 12 Feb 2026 |
Recent insider transactions for Aon plc
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Notebaert Richard C | AON | Class A Ordinary Stock | Gift | -4.93% | -1,438 | 27,738 | 12 May 2026 | Direct | ||
| Anne Corona | AON | Class A Ordinary Stock | Tax liability | -3.82% | -163 | 4,098 | 13 Mar 2026 | Direct | ||
| Anne Corona | AON | Class A Ordinary Stock | Options Exercise | 9.4% | 367 | 4,272 | 13 Mar 2026 | Direct | ||
| Anne Corona | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -100% | -367 | 0 | 13 Mar 2026 | Direct | ||
| Lori Goltermann | AON | Class A Ordinary Stock | Tax liability | -3.29% | -225 | 6,632 | 13 Mar 2026 | Direct | ||
| Lori Goltermann | AON | Class A Ordinary Stock | Options Exercise | 8.09% | 518 | 6,922 | 13 Mar 2026 | Direct | ||
| Lori Goltermann | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -100% | -518 | 0 | 13 Mar 2026 | Direct | ||
| Andy Marcell | AON | Class A Ordinary Stock | Tax liability | -8.47% | -794 | 8,582 | 13 Mar 2026 | Direct | ||
| Andy Marcell | AON | Class A Ordinary Stock | Options Exercise | 21.7% | 1,630 | 9,149 | 13 Mar 2026 | Direct | ||
| Andy Marcell | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -100% | -1,630 | 0 | 13 Mar 2026 | Direct | ||
| Darren Zeidel | AON | Class A Ordinary Stock | Sale | -21.2% | $1,417,784 | $329.72 | -4,300 | 15,954 | 26 Feb 2026 | Direct |
| Gregory C. Case | AON | Class A Ordinary Stock | Gift | 14.7% | 22,412 | 175,170 | 19 Feb 2026 | By Trust | ||
| Gregory C. Case | AON | Class A Ordinary Stock | Gift | -100% | -37,412 | 0 | 19 Feb 2026 | By GRAT | ||
| Lisa Stevens | AON | Class A Ordinary Stock | Gift | -0.12% | -32 | 26,321 | 18 Feb 2026 | Direct | ||
| Gregory C. Case | AON | Class A Ordinary Stock | Gift | 5.11% | 6,428 | 132,243 | 17 Feb 2026 | By Trust | ||
| Gregory C. Case | AON | Class A Ordinary Stock | Gift | -0.68% | -6,428 | 933,709 | 17 Feb 2026 | Direct | ||
| Gregory C. Case | AON | Class A Ordinary Stock | Tax liability | -0.11% | -1,002 | 940,137 | 17 Feb 2026 | Direct | ||
| Gregory C. Case | AON | Class A Ordinary Stock | Options Exercise | 0.25% | 2,357 | 941,139 | 17 Feb 2026 | Direct | ||
| Gregory C. Case | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -100% | -2,357 | 0 | 17 Feb 2026 | Direct | ||
| Darren Zeidel | AON | Class A Ordinary Stock | Sale | -19.9% | $1,641,982 | $325.79 | -5,040 | 20,254 | 17 Feb 2026 | Direct |
| Darren Zeidel | AON | Class A Ordinary Stock | Tax liability | -1.86% | -478 | 25,178 | 13 Feb 2026 | Direct | ||
| Darren Zeidel | AON | Class A Ordinary Stock | Options Exercise | 4.41% | 1,080 | 25,564 | 13 Feb 2026 | Direct | ||
| Darren Zeidel | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -100% | -1,080 | 0 | 13 Feb 2026 | Direct | ||
| Lisa Stevens | AON | Class A Ordinary Stock | Tax liability | -3.45% | -932 | 26,107 | 13 Feb 2026 | Direct | ||
| Lisa Stevens | AON | Class A Ordinary Stock | Options Exercise | 7.75% | 1,929 | 26,808 | 13 Feb 2026 | Direct | ||
| Lisa Stevens | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -100% | -1,929 | 0 | 13 Feb 2026 | Direct | ||
| Mindy F. Simon | AON | Class A Ordinary Stock | Tax liability | -1.65% | -109 | 6,496 | 13 Feb 2026 | Direct | ||
| Mindy F. Simon | AON | Class A Ordinary Stock | Options Exercise | 4% | 254 | 6,605 | 13 Feb 2026 | Direct | ||
| Mindy F. Simon | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -33.3% | -254 | 508 | 13 Feb 2026 | Direct | ||
| Edmund Reese | AON | Class A Ordinary Stock | Tax liability | -10.6% | -251 | 2,124 | 13 Feb 2026 | Direct | ||
| Edmund Reese | AON | Class A Ordinary Stock | Options Exercise | 33.6% | 598 | 2,375 | 13 Feb 2026 | Direct | ||
| Edmund Reese | AON | Restricted Share Unit (Right to Receive) | Options Exercise | -33.3% | -598 | 1,196 | 13 Feb 2026 | Direct | ||
| Darren Zeidel | AON | Class A Ordinary Stock | Tax liability | -9.84% | -2,696 | 24,693 | 12 Feb 2026 | Direct | ||
| Darren Zeidel | AON | Class A Ordinary Stock | Award | 35.2% | 7,135 | 27,388 | 12 Feb 2026 | Direct | ||
| Darren Zeidel | AON | Restricted Share Unit (Right to Receive) | Award | 1,113 | 1,113 | 12 Feb 2026 | Direct | |||
| Lisa Stevens | AON | Class A Ordinary Stock | Tax liability | -23% | -7,568 | 25,357 | 12 Feb 2026 | Direct | ||
| Lisa Stevens | AON | Class A Ordinary Stock | Award | 92.9% | 15,856 | 32,925 | 12 Feb 2026 | Direct | ||
| Lisa Stevens | AON | Restricted Share Unit (Right to Receive) | Award | 2,059 | 2,059 | 12 Feb 2026 | Direct | |||
| Mindy F. Simon | AON | Class A Ordinary Stock | Tax liability | -27.2% | -2,378 | 6,351 | 12 Feb 2026 | Direct | ||
| Mindy F. Simon | AON | Class A Ordinary Stock | Award | 174.6% | 5,550 | 8,729 | 12 Feb 2026 | Direct | ||
| Mindy F. Simon | AON | Restricted Share Unit (Right to Receive) | Award | 1,113 | 1,113 | 12 Feb 2026 | Direct | |||
| Edmund Reese | AON | Restricted Share Unit (Right to Receive) | Award | 2,337 | 2,337 | 12 Feb 2026 | Direct | |||
| Andy Marcell | AON | Class A Ordinary Stock | Tax liability | -45.2% | -6,576 | 7,983 | 12 Feb 2026 | Direct | ||
| Andy Marcell | AON | Class A Ordinary Stock | Award | 768% | 12,882 | 14,559 | 12 Feb 2026 | Direct | ||
| Andy Marcell | AON | Restricted Share Unit (Right to Receive) | Award | 11,765 | 9,539 | 12 Feb 2026 | Direct | |||
| Lori Goltermann | AON | Class A Ordinary Stock | Tax liability | -29.4% | -2,713 | 6,503 | 12 Feb 2026 | Direct | ||
| Lori Goltermann | AON | Class A Ordinary Stock | Award | 304.4% | 6,937 | 9,216 | 12 Feb 2026 | Direct | ||
| Lori Goltermann | AON | Restricted Share Unit (Right to Receive) | Award | 1,113 | 1,113 | 12 Feb 2026 | Direct | |||
| Anne Corona | AON | Class A Ordinary Stock | Tax liability | -26% | -1,405 | 3,990 | 12 Feb 2026 | Direct | ||
| Anne Corona | AON | Class A Ordinary Stock | Award | 142.6% | 3,171 | 5,395 | 12 Feb 2026 | Direct |
* marks a reported price that did not pass the local price check.