Arthur J. Gallagher & Co.
MX ˙ BMV ˙ US3635761097
SecurityMX:AJG / Arthur J. Gallagher & Co.
InstitutionCalamos Advisors LLC
Latest Disclosed Ownership85,528 shares
Latest Disclosed Value $ 18,523,654
Calamos Advisors LLC ownership in AJG / Arthur J. Gallagher & Co.

On May 4, 2026 - Calamos Advisors LLC filed a 13F-HR form disclosing ownership of 85,528 shares of Arthur J. Gallagher & Co. (MX:AJG) valued at $18,523,654 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 29, 2026 disclosing 85,528 shares of Arthur J. Gallagher & Co.. This represents a change in shares of 0.00% 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)
2026-05-04 2026-03-31 13F GALLAGHER ARTHUR J COM 363576109 85,528 0 0.00 18,524 -16.31 0.0653
2026-01-29 2025-12-31 13F GALLAGHER ARTHUR J COM 363576109 85,528 -3,108 -3.51 22,134 -19.38 0.0831
2025-10-20 2025-09-30 13F GALLAGHER ARTHUR J COM 363576109 88,636 0 0.00 27,454 -3.24 0.1014
2025-08-08 2025-06-30 13F GALLAGHER ARTHUR J COM 363576109 88,636 0 0.00 28,374 -7.27 0.1117
2025-04-29 2025-03-31 13F GALLAGHER ARTHUR J COM 363576109 88,636 987 1.13 30,601 23.00 0.1332
2025-01-24 2024-12-31 13F GALLAGHER ARTHUR J COM 363576109 87,649 0 0.00 24,879 0.88 0.1040
2024-11-07 2024-09-30 13F GALLAGHER ARTHUR J COM 363576109 87,649 -2,150 -2.39 24,662 5.91 0.1066
2024-07-25 2024-06-30 13F GALLAGHER ARTHUR J COM 363576109 89,799 -3,278 -3.52 23,286 0.06 0.1034
2024-05-08 2024-03-31 13F GALLAGHER ARTHUR J COM 363576109 93,077 -2,341 -2.45 23,273 8.46 0.1103
2024-01-31 2023-12-31 13F GALLAGHER ARTHUR J COM 363576109 95,418 -1,246 -1.29 21,458 -2.61 0.1041
2023-10-26 2023-09-30 13F GALLAGHER ARTHUR J COM 363576109 96,664 0 0.00 22,033 3.81 0.1145
2023-07-28 2023-06-30 13F GALLAGHER ARTHUR J COM 363576109 96,664 0 0.00 21,225 14.77 0.1050
2023-05-04 2023-03-31 13F GALLAGHER ARTHUR J COM 363576109 96,664 -12,085 -11.11 18,493 -9.81 0.0903
2023-01-26 2022-12-31 13F GALLAGHER ARTHUR J COM 363576109 108,749 -19,228 -15.02 20,504 -6.43 0.0962
2022-10-24 2022-09-30 13F GALLAGHER ARTHUR J COM 363576109 127,977 0 0.00 21,912 5.02 0.1002
2022-08-01 2022-06-30 13F GALLAGHER ARTHUR J COM 363576109 127,977 3,446 2.77 20,865 -4.04 0.0900
2022-05-03 2022-03-31 13F GALLAGHER ARTHUR J COM 363576109 124,531 16,598 15.38 21,743 18.73 0.0816
2022-02-01 2021-12-31 13F GALLAGHER ARTHUR J COM 363576109 107,933 4,178 4.03 18,313 18.74 0.0685
2021-10-26 2021-09-30 13F GALLAGHER ARTHUR J COM 363576109 103,755 9,155 9.68 15,423 16.38 0.0674
2021-07-22 2021-06-30 13F GALLAGHER ARTHUR J COM 363576109 94,600 21,517 29.44 13,252 45.32 0.0605
2021-04-12 2021-03-31 13F GALLAGHER ARTHUR J COM 363576109 73,083 2,259 3.19 9,119 4.07 0.0497
2021-01-27 2020-12-31 13F GALLAGHER ARTHUR J COM 363576109 70,824 -3,068 -4.15 8,762 12.30 0.0509
2020-10-26 2020-09-30 13F GALLAGHER ARTHUR J COM 363576109 73,892 -6,485 -8.07 7,802 -0.43 0.0502
2020-07-27 2020-06-30 13F GALLAGHER ARTHUR J COM 363576109 80,377 -5,143 -6.01 7,836 12.41 0.0554
2020-04-28 2020-03-31 13F GALLAGHER ARTHUR J COM 363576109 85,520 -7,284 -7.85 6,971 -21.12 0.0547
2020-01-15 2019-12-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 92,804 -1,520 -1.61 8,838 4.60 0.0437
2019-10-21 2019-09-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 94,324 8,191 9.51 8,449 12.00 0.0460
2019-08-07 2019-06-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 86,133 -28,777 -25.04 7,544 -15.93 0.0419
2019-04-12 2019-03-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 114,910 1,160 1.02 8,974 7.05 0.0560
2019-01-24 2018-12-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 113,750 17,031 17.61 8,383 16.43 0.0553
2018-10-22 2018-09-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 96,719 6,192 6.84 7,200 21.83 0.0396
2018-07-17 2018-06-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 90,527 -18,592 -17.04 5,910 -21.20 0.0361
2018-04-13 2018-03-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 109,119 5,145 4.95 7,500 14.00 0.0488
2018-02-13 2017-12-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 103,974 -2,205 -2.08 6,579 0.67 0.0335
2017-10-25 2017-09-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 106,179 3,892 3.80 6,535 11.59 0.0505
2017-08-09 2017-06-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 102,287 102,287 5,856 0.0433
2016-02-05 2015-12-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 0 -857,050 -100.00 0 -100.00
2015-11-10 2015-09-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 857,050 -615,480 -41.80 35,379 -49.21 0.2438
2015-08-14 2015-06-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 1,472,530 -6,234 -0.42 69,651 0.75 0.4302
2015-05-13 2015-03-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 1,478,764 60,262 4.25 69,132 3.52 0.4333
2015-02-13 2014-12-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 1,418,502 -3,728 -0.26 66,783 3.52 0.4417
2014-11-14 2014-09-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 1,422,230 -45,881 -3.13 64,512 -5.70 0.4305
2014-08-14 2014-06-30 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 1,468,111 737,071 100.82 68,414 96.69 0.4336
2014-05-16 2014-03-31 13F ARTHUR J GALLAGHER COMMON STOCK 363576109 731,040 731,040 34,783 0.2223
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.