Arthur J. Gallagher & Co.
MX ˙ BMV ˙ US3635761097
SecurityMX:AJG / Arthur J. Gallagher & Co.
InstitutionNorthern Trust Corp
Latest Disclosed Ownership2,229,829 shares
Latest Disclosed Value $ 482,936,365
Northern Trust Corp reports 0.02% decrease in ownership of AJG / Arthur J. Gallagher & Co.

On May 14, 2026 - Northern Trust Corp filed a 13F-HR form disclosing ownership of 2,229,829 shares of Arthur J. Gallagher & Co. (MX:AJG) valued at $482,936,365 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 2,230,272 shares of Arthur J. Gallagher & Co.. This represents a change in shares of -0.02% 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)
2026-05-14 2026-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,229,829 -443 -0.02 482,936 -16.33 0.0131
2026-02-17 2025-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,230,272 -87,079 -3.76 577,172 -19.59 0.0736
2025-11-14 2025-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,317,351 -30,992 -1.32 717,776 -4.52 0.0918
2025-08-13 2025-06-30 13F GALLAGHER ARTHUR J COM 363576109 2,348,343 -16,416 -0.69 751,752 -7.92 0.1034
2025-05-13 2025-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,364,759 9,458 0.40 816,409 22.12 0.1212
2025-02-14 2024-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,355,301 480,193 25.61 668,552 26.72 0.0947
2024-11-13 2024-09-30 13F GALLAGHER ARTHUR J COM 363576109 1,875,108 -85,286 -4.35 527,599 3.79 0.0864
2024-08-14 2024-06-30 13F GALLAGHER ARTHUR J COM 363576109 1,960,394 39,440 2.05 508,350 5.84 0.0857
2024-05-14 2024-03-31 13F GALLAGHER ARTHUR J COM 363576109 1,920,954 -124,435 -6.08 480,315 4.42 0.0830
2024-02-13 2023-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,045,389 -46,094 -2.20 459,967 -3.51 0.0833
2023-11-13 2023-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,091,483 107,176 5.40 476,712 9.41 0.0923
2023-08-11 2023-06-30 13F GALLAGHER ARTHUR J COM 363576109 1,984,307 -106,778 -5.11 435,694 8.91 0.0837
2023-05-15 2023-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,091,085 6,321 0.30 400,045 1.78 0.0793
2023-02-13 2022-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,084,764 23,070 1.12 393,061 11.35 0.0825
2022-11-14 2022-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,061,694 -9,189 -0.44 353,003 4.55 0.0806
2022-08-12 2022-06-30 13F GALLAGHER ARTHUR J COM 363576109 2,070,883 -56,871 -2.67 337,637 -9.12 0.0723
2022-05-13 2022-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,127,754 1,187 0.06 371,505 2.96 0.0654
2022-02-08 2021-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,126,567 2,518 0.12 360,815 14.28 0.0591
2021-11-15 2021-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,124,049 16,569 0.79 315,739 6.95 0.0559
2021-08-13 2021-06-30 13F GALLAGHER ARTHUR J COM 363576109 2,107,480 58,480 2.85 295,215 15.47 0.0520
2021-05-12 2021-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,049,000 -22,775 -1.10 255,654 -0.25 0.0476
2021-02-11 2020-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,071,775 -38,821 -1.84 256,299 15.02 0.0499
2020-11-16 2020-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,110,596 5,165 0.25 222,837 8.56 0.0489
2020-08-14 2020-06-30 13F GALLAGHER ARTHUR J COM 363576109 2,105,431 -37,045 -1.73 205,259 17.54 0.0486
2020-05-14 2020-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,142,476 23,169 1.09 174,634 -13.47 0.0501
2020-02-14 2019-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,119,307 17,539 0.83 201,822 7.21 0.0452
2019-11-13 2019-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,101,768 7,092 0.34 188,256 2.61 0.0451
2019-08-13 2019-06-30 13F GALLAGHER ARTHUR J COM 363576109 2,094,676 3,106 0.15 183,473 12.32 0.0435
2019-05-13 2019-03-31 13F GALLAGHER ARTHUR J COM 363576109 2,091,570 25,111 1.22 163,351 7.26 0.0403
2019-02-12 2018-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,066,459 103,958 5.30 152,299 4.25 0.0427
2018-11-14 2018-09-30 13F GALLAGHER ARTHUR J COM 363576109 1,962,501 -7,158 -0.36 146,089 13.62 0.0358
2018-09-18 2018-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 1,969,659 -29,220 -1.46 128,579 -6.41 0.0327
2018-08-14 2018-06-30 13F GALLAGHER ARTHUR J COM 363576109 1,981,201 -17,678 129,332
2018-05-09 2018-03-31 13F GALLAGHER ARTHUR J COM 363576109 1,998,879 -65,683 -3.18 137,383 5.16 0.0357
2018-02-14 2017-12-31 13F GALLAGHER ARTHUR J COM 363576109 2,064,562 -14,599 -0.70 130,645 2.09 0.0331
2017-11-13 2017-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,079,161 143,036 7.39 127,972 15.45 0.0334
2017-08-11 2017-06-30 13F GALLAGHER ARTHUR J COM 363576109 1,936,125 -14,035 -0.72 110,843 0.53 0.0310
2017-05-12 2017-03-31 13F GALLAGHER ARTHUR J COM 363576109 1,950,160 24,839 1.29 110,262 10.22 0.0318
2017-02-13 2016-12-31 13F GALLAGHER ARTHUR J COM 363576109 1,925,321 47,954 2.55 100,041 4.75 0.0307
2016-11-09 2016-09-30 13F GALLAGHER ARTHUR J COM 363576109 1,877,367 63,432 3.50 95,502 10.61 0.0297
2016-08-12 2016-06-30 13F GALLAGHER ARTHUR J COM 363576109 1,813,935 281,283 18.35 86,344 27.27 0.0280
2016-08-19 2016-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 1,532,652 -759,472 -33.13 67,844 -27.70 0.0225
2016-05-13 2016-03-31 13F Gallagher Arthur J COMM 363576109 1,532,652 68,173
2016-02-12 2015-12-31 13F Gallagher Arthur J COMM 363576109 2,292,124 -39,554 -1.70 93,839 -2.51 0.0311
2015-11-12 2015-09-30 13F GALLAGHER ARTHUR J COM 363576109 2,331,678 38,818 1.69 96,252 -11.25 0.0321
2015-08-13 2015-06-30 13F GALLAGHER ARTHUR J COM 363576109 2,292,860 201,829 9.65 108,453 10.94 0.0735
2015-08-13 2015-06-30 13F Gallagher Arthur J COMM 036357610 32,069 -2,058,962 1,517 0.0010
2015-05-14 2015-03-31 13F Gallagher Arthur J COMM 363576109 2,091,031 -25,433 -1.20 97,755 -1.90 0.0294
2015-02-12 2014-12-31 13F Gallagher Arthur J COM 363576109 2,116,464 39,393 1.90 99,644 5.76 0.0301
2014-11-13 2014-09-30 13F Gallagher Arthur J COMM 363576109 2,077,071 -65,860 -3.07 94,216 -5.65 0.0296
2014-08-14 2014-06-30 13F GALLAGHER ARTHUR J com 363576109 2,142,931 247,034 13.03 99,860 10.70 0.0311
2014-05-14 2014-03-31 13F GALLAGHER ARTHUR J COMM 363576109 1,895,897 -16,648 -0.87 90,207 0.50 0.0284
2014-02-21 2013-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 1,912,545 14,577 0.77 89,755 8.34 0.0288
2014-02-12 2013-12-31 13F GALLAGHER ARTHUR J COM 363576109 1,912,545 89,755
2013-11-13 2013-09-30 13F GALLAGHER ARTHUR J COM 363576109 1,897,968 29,441 1.58 82,846 1.48 0.0292
2013-08-09 2013-06-30 13F GALLAGHER ARTHUR J COM 363576109 1,868,527 1,868,527 81,636 0.0296
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.