Arthur J. Gallagher & Co.
MX ˙ BMV ˙ US3635761097
SecurityMX:AJG / Arthur J. Gallagher & Co.
InstitutionRhumbline Advisers
Latest Disclosed Ownership428,774 shares
Latest Disclosed Value $ 92,863,737
Rhumbline Advisers reports 3.18% decrease in ownership of AJG / Arthur J. Gallagher & Co.

On May 12, 2026 - Rhumbline Advisers filed a 13F-HR form disclosing ownership of 428,774 shares of Arthur J. Gallagher & Co. (MX:AJG) valued at $92,863,737 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 442,872 shares of Arthur J. Gallagher & Co.. This represents a change in shares of -3.18% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-12 2026-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 428,774 -14,098 -3.18 92,864 -18.97 0.0794
2026-02-13 2025-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 442,872 -9,056 -2.00 114,611 -18.12 0.0927
2025-11-06 2025-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 451,928 -902 -0.20 139,980 -3.43 0.1124
2025-08-12 2025-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 452,830 -6,829 -1.49 144,960 -8.65 0.1241
2025-05-29 2025-03-31 13F/A-1 GALLAGHER ARTHUR J & CO COM COM 363576109 459,659 38,564 9.16 158,693 32.77 0.1484
2025-04-08 2025-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 459,659 38,564 158,693 0.1484
2025-05-29 2024-12-31 13F/A-1 GALLAGHER ARTHUR J & CO COM COM 363576109 421,095 20,044 5.00 119,528 5.92 0.1069
2025-01-30 2024-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 421,095 20,044 119,528 0.1069
2024-11-12 2024-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 401,051 -28,439 -6.62 112,844 1.32 0.1018
2024-08-01 2024-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 429,490 -2,437 -0.56 111,371 3.12 0.1047
2024-05-09 2024-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 431,927 25,510 6.28 107,999 18.17 0.1037
2024-02-08 2023-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 406,417 -759 -0.19 91,395 -1.52 0.0958
2023-11-09 2023-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 407,176 -2,329 -0.57 92,808 3.22 0.1077
2023-08-08 2023-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 409,505 10,068 2.52 89,915 118,209.21 0.1007
2023-05-11 2023-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 399,437 9,724 2.50 76 -99.90 0.0943
2023-02-14 2022-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 389,713 23,118 6.31 73,476 17.06 0.0988
2022-11-10 2022-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 366,595 12,973 3.67 62,768 8.87 0.0935
2022-08-11 2022-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 353,622 42,835 13.78 57,655 6.25 0.0841
2022-05-12 2022-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 310,787 7,552 2.49 54,263 5.47 0.0698
2022-02-10 2021-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 303,235 4,613 1.54 51,450 15.90 0.0631
2021-11-12 2021-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 298,622 -9,222 -3.00 44,390 2.94 0.0601
2021-08-05 2021-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 307,844 2,470 0.81 43,123 13.18 0.0566
2021-05-06 2021-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 305,374 -14,337 -4.48 38,102 -3.66 0.0518
2021-02-10 2020-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 319,711 7,370 2.36 39,551 19.94 0.0546
2020-11-12 2020-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 312,341 -4,181 -1.32 32,977 6.87 0.0517
2020-08-13 2020-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 316,522 -27,256 -7.93 30,858 10.12 0.0515
2020-05-06 2020-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 343,778 11,306 3.40 28,021 -11.50 0.0587
2020-02-05 2019-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 332,472 13,794 4.33 31,661 10.92 0.0530
2019-10-23 2019-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 318,678 5,179 1.65 28,544 3.95 0.0522
2019-08-14 2019-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 313,499 15,440 5.18 27,459 17.96 0.0515
2019-05-01 2019-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 298,059 -28,901 -8.84 23,278 -3.40 0.0451
2019-01-31 2018-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 326,960 68 0.02 24,097 -0.97 0.0524
2018-11-07 2018-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 326,892 -2,125 -0.65 24,334 13.30 0.0470
2018-08-06 2018-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 329,017 -27,078 -7.60 21,478 -12.24 0.0433
2018-05-02 2018-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 356,095 -8,509 -2.33 24,474 6.08 0.0511
2018-02-09 2017-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 364,604 3,993 1.11 23,072 3.95 0.0469
2017-11-06 2017-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 360,611 5,061 1.42 22,196 9.04 0.0483
2017-08-02 2017-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 355,550 19,175 5.70 20,355 7.02 0.0465
2017-05-02 2017-03-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 336,375 8,613 2.63 19,019 11.67 0.0444
2017-01-27 2016-12-31 13F GALLAGHER ARTHUR J & CO COM COM 363576109 327,762 52,740 19.18 17,031 21.74 0.0432
2016-11-08 2016-09-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 275,022 -4,435 -1.59 13,990 5.17 0.0385
2016-08-11 2016-06-30 13F GALLAGHER ARTHUR J & CO COM COM 363576109 279,457 -28,901 -9.37 13,302 -3.02 0.0394
2016-05-02 2016-03-31 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 308,358 36,020 13.23 13,716 23.01 0.0426
2016-02-03 2015-12-31 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 272,338 5,552 2.08 11,150 1.24 0.0359
2015-11-04 2015-09-30 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 266,786 -11,065 -3.98 11,013 -16.20 0.0375
2015-08-04 2015-06-30 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 277,851 2,440 0.89 13,142 2.07 0.0419
2015-05-12 2015-03-31 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 275,411 54,973 24.94 12,875 24.06 0.0371
2015-02-06 2014-12-31 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 220,438 2,755 1.27 10,378 5.10 0.0301
2014-11-12 2014-09-30 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 217,683 -31,983 -12.81 9,874 -15.13 0.0297
2014-08-06 2014-06-30 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 249,666 10,553 4.41 11,634 2.26 0.0341
2014-05-06 2014-03-31 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 239,113 38,234 19.03 11,377 20.69 0.0337
2014-02-03 2013-12-31 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 200,879 -17,287 -7.92 9,427 -1.01 0.0278
2013-11-05 2013-09-30 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 218,166 -1 -0.00 9,523 -0.09 0.0295
2013-08-07 2013-06-30 13F ARTHUR J GALLAGHER + CO COMMON COM 363576109 218,167 218,167 9,532 0.0306
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.