Arthur J. Gallagher & Co.
US ˙ NYSE ˙ US3635761097

SecurityAJG / Arthur J. Gallagher & Co.
InstitutionAsset Management One Co., Ltd.
Latest Disclosed Ownership127,509 shares
Latest Disclosed Value $ 27,615,899
Asset Management One Co., Ltd. reports 0.01% decrease in ownership of AJG / Arthur J. Gallagher & Co.

On May 8, 2026 - Asset Management One Co., Ltd. filed a 13F-HR form disclosing ownership of 127,509 shares of Arthur J. Gallagher & Co. (US:AJG) valued at $27,615,899 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 27, 2026 disclosing 127,525 shares of Arthur J. Gallagher & Co.. This represents a change in shares of -0.01% during the quarter. The current value of the position is $26,904,399 USD.

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.

Upgrade to unlock premium data and export to Excel .

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)
2026-05-08 2026-03-31 13F GALLAGHER ARTHUR J COM 363576109 127,509 -16 -0.01 27,616 -17.69 0.0814
2026-01-27 2025-12-31 13F GALLAGHER ARTHUR J COM 363576109 127,525 13,775 12.11 33,549 -4.78 0.0933
2025-10-22 2025-09-30 13F GALLAGHER ARTHUR J COM 363576109 113,750 1,786 1.60 35,233 -1.70 0.1021
2025-07-31 2025-06-30 13F GALLAGHER ARTHUR J COM 363576109 111,964 3,830 3.54 35,842 -3.99 0.1124
2025-04-23 2025-03-31 13F GALLAGHER ARTHUR J COM 363576109 108,134 10,216 10.43 37,332 33.06 0.1291
2025-01-30 2024-12-31 13F GALLAGHER ARTHUR J COM 363576109 97,918 13,242 15.64 28,057 17.76 0.0964
2024-10-30 2024-09-30 13F GALLAGHER ARTHUR J COM 363576109 84,676 998 1.19 23,825 9.80 0.0848
2024-07-18 2024-06-30 13F GALLAGHER ARTHUR J COM 363576109 83,678 -2,433 -2.83 21,699 0.78 0.0830
2024-05-02 2024-03-31 13F GALLAGHER ARTHUR J COM 363576109 86,111 -2,461 -2.78 21,531 8.79 0.0830
2024-01-24 2023-12-31 13F GALLAGHER ARTHUR J COM 363576109 88,572 -1,138 -1.27 19,792 -3.20 0.0797
2023-10-19 2023-09-30 13F GALLAGHER ARTHUR J COM 363576109 89,710 486 0.54 20,448 4.37 0.0910
2023-07-31 2023-06-30 13F GALLAGHER ARTHUR J COM 363576109 89,224 -5,055 -5.36 19,591 8.62 0.0829
2023-04-25 2023-03-31 13F GALLAGHER ARTHUR J COM 363576109 94,279 2,619 2.86 18,037 3.50 0.0817
2023-02-06 2022-12-31 13F GALLAGHER ARTHUR J COM 363576109 91,660 -1,480 -1.59 17,426 9.27 0.0849
2022-11-04 2022-09-30 13F GALLAGHER ARTHUR J COM 363576109 93,140 -557 -0.59 15,947 4.39 0.0811
2022-07-29 2022-06-30 13F GALLAGHER ARTHUR J COM 363576109 93,697 -4,287 -4.38 15,276 -10.71 0.0717
2022-05-13 2022-03-31 13F GALLAGHER ARTHUR J COM 363576109 97,984 -5,762 -5.55 17,108 -2.88 0.0668
2022-02-09 2021-12-31 13F GALLAGHER ARTHUR J COM 363576109 103,746 -48 -0.05 17,616 14.18 0.0614
2021-11-02 2021-09-30 13F GALLAGHER ARTHUR J COM 363576109 103,794 341 0.33 15,428 6.47 0.0591
2021-08-03 2021-06-30 13F GALLAGHER ARTHUR J COM 363576109 103,453 -90 -0.09 14,491 12.17 0.0539
2021-05-14 2021-03-31 13F GALLAGHER ARTHUR J COM 363576109 103,543 7,024 7.28 12,919 10.08 0.0513
2021-02-12 2020-12-31 13F GALLAGHER ARTHUR J COM 363576109 96,519 1,874 1.98 11,736 17.45 0.0483
2020-11-13 2020-09-30 13F GALLAGHER ARTHUR J COM 363576109 94,645 -2,482 -2.56 9,992 5.50 0.0459
2020-08-14 2020-06-30 13F GALLAGHER ARTHUR J COM 363576109 97,127 -13,661 -12.33 9,471 4.86 0.0466
2020-05-14 2020-03-31 13F GALLAGHER ARTHUR J COM 363576109 110,788 11,405 11.48 9,032 -4.56 0.0527
2020-02-14 2019-12-31 13F GALLAGHER ARTHUR J COM 363576109 99,383 -1,867 -1.84 9,464 4.38 0.0427
2019-11-14 2019-09-30 13F GALLAGHER ARTHUR J COM 363576109 101,250 7,275 7.74 9,067 10.14 0.0437
2019-08-14 2019-06-30 13F GALLAGHER ARTHUR J COM 363576109 93,975 10,128 12.08 8,232 25.72 0.0404
2019-05-15 2019-03-31 13F GALLAGHER ARTHUR J COM 363576109 83,847 -213,757 -71.83 6,548 -70.11 0.0354
2019-02-13 2018-12-31 13F GALLAGHER ARTHUR J COM 363576109 297,604 2,525 0.86 21,907 -0.27 0.0522
2018-11-14 2018-09-30 13F GALLAGHER ARTHUR J COM 363576109 295,079 23,502 8.65 21,966 23.92 0.0451
2018-08-14 2018-06-30 13F GALLAGHER ARTHUR J COM 363576109 271,577 2,059 0.76 17,726 -4.31 0.0387
2018-05-14 2018-03-31 13F GALLAGHER ARTHUR J COM 363576109 269,518 1,182 0.44 18,524 9.06 0.0417
2018-02-14 2017-12-31 13F GALLAGHER ARTHUR J COM 363576109 268,336 -2,609 -0.96 16,985 1.85 0.0375
2017-11-14 2017-09-30 13F GALLAGHER ARTHUR J COM 363576109 270,945 -154,242 -36.28 16,676 -31.38 0.0391
2017-08-14 2017-06-30 13F GALLAGHER ARTHUR J COM 363576109 425,187 155,349 57.57 24,303 59.27 0.0620
2017-05-11 2017-03-31 13F GALLAGHER ARTHUR J COM 363576109 269,838 -22,981 -7.85 15,259 0.31 0.0401
2017-05-02 2016-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 292,819 277,917 1,864.96 15,212 1,925.57 0.0389
2017-02-13 2016-12-31 13F GALLAGHER ARTHUR J COM 363576109 292,819 15,212
2016-11-07 2016-09-30 13F ARTHUR J GALLAGHER Com 363576109 14,902 -35,518 -70.44 751 -67.89 0.0112
2016-08-03 2016-06-30 13F ARTHUR J GALLAGHER Com 363576109 50,420 35,654 241.46 2,339 257.10 0.0351
2016-05-05 2016-03-31 13F ARTHUR J GALLAGHER Com 363576109 14,766 0 0.00 655 7.20 0.0096
2016-01-28 2015-12-31 13F ARTHUR J GALLAGHER Com 363576109 14,766 0 0.00 611 1.33 0.0091
2015-11-12 2015-09-30 13F ARTHUR J GALLAGHER Com 363576109 14,766 5,000 51.20 603 30.80 0.0092
2015-08-06 2015-06-30 13F ARTHUR J GALLAGHER Com 363576109 9,766 -39,160 -80.04 461 -79.90 0.0064
2014-05-05 2014-03-31 13F ARTHUR J GALLAGHER COM 363576109 48,926 0 0.00 2,293 1.10 0.0361
2014-02-05 2013-12-31 13F/A-1 ARTHUR J GALLAGHER COM 363576109 48,926 48,926 2,268 0.0351
2014-01-29 2013-12-31 13F ARTHUR J GALLAGHER COM 363576109 48,926 2,268
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.