Arthur J. Gallagher & Co.
MX ˙ BMV ˙ US3635761097
SecurityMX:AJG / Arthur J. Gallagher & Co.
InstitutionAssenagon Asset Management S.A.
Latest Disclosed Ownership62,280 shares
Latest Disclosed Value $ 13,488,602
Assenagon Asset Management S.A. reports 56.26% increase in ownership of AJG / Arthur J. Gallagher & Co.

On April 20, 2026 - Assenagon Asset Management S.A. filed a 13F-HR form disclosing ownership of 62,280 shares of Arthur J. Gallagher & Co. (MX:AJG) valued at $13,488,602 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 9, 2026 disclosing 39,857 shares of Arthur J. Gallagher & Co.. This represents a change in shares of 56.26% 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.

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)
2026-04-20 2026-03-31 13F GALLAGHER ARTHUR J COM 363576109 62,280 22,423 56.26 13,489 30.77 0.0205
2026-01-09 2025-12-31 13F GALLAGHER ARTHUR J COM 363576109 39,857 -321,149 -88.96 10,315 -90.78 0.0142
2025-10-07 2025-09-30 13F GALLAGHER ARTHUR J COM 363576109 361,006 -7,431 -2.02 111,818 -5.19 0.1529
2025-07-11 2025-06-30 13F GALLAGHER ARTHUR J COM 363576109 368,437 249,616 210.08 117,944 187.52 0.1751
2025-04-15 2025-03-31 13F GALLAGHER ARTHUR J COM 363576109 118,821 -318,643 -72.84 41,022 -66.96 0.0684
2025-01-14 2024-12-31 13F GALLAGHER ARTHUR J COM 363576109 437,464 430,917 6,581.90 124,174 6,641.26 0.2003
2024-10-23 2024-09-30 13F GALLAGHER ARTHUR J COM 363576109 6,547 2,110 47.55 1,842 60.17 0.0034
2024-07-18 2024-06-30 13F GALLAGHER ARTHUR J COM 363576109 4,437 201 4.75 1,151 8.59 0.0026
2024-04-24 2024-03-31 13F GALLAGHER ARTHUR J COM 363576109 4,236 -65,816 -93.95 1,059 -93.28 0.0025
2024-01-17 2023-12-31 13F GALLAGHER ARTHUR J COM 363576109 70,052 -182,171 -72.23 15,753 -72.60 0.0418
2023-11-06 2023-09-30 13F GALLAGHER ARTHUR J COM 363576109 252,223 193,034 326.13 57,489 342.36 0.1780
2023-07-25 2023-06-30 13F GALLAGHER ARTHUR J COM 363576109 59,189 55,229 1,394.67 12,996 1,616.78 0.0450
2023-04-18 2023-03-31 13F GALLAGHER ARTHUR J COM 363576109 3,960 -31,752 -88.91 758 12,516.67 0.0027
2023-01-12 2022-12-31 13F GALLAGHER ARTHUR J COM 363576109 35,712 30,515 587.17 7 -99.33 0.0243
2022-10-27 2022-09-30 13F GALLAGHER ARTHUR J COM 363576109 5,197 -59,906 -92.02 890 -91.61 0.0034
2022-07-27 2022-06-30 13F GALLAGHER ARTHUR J COM 363576109 65,103 63,438 3,810.09 10,614 3,547.42 0.0393
2022-04-25 2022-03-31 13F GALLAGHER ARTHUR J COM 363576109 1,665 -2,469 -59.72 291 -58.49 0.0008
2022-02-01 2021-12-31 13F GALLAGHER ARTHUR J COM 363576109 4,134 -305,888 -98.67 701 -98.48 0.0020
2021-10-19 2021-09-30 13F GALLAGHER ARTHUR J COM 363576109 310,022 310,022 46,085 0.1474
2021-07-15 2021-06-30 13F GALLAGHER ARTHUR J COM 363576109 0 -24,661 -100.00 0 -100.00
2021-04-26 2021-03-31 13F GALLAGHER ARTHUR J COM 363576109 24,661 24,661 3,077 0.0125
2021-02-01 2020-12-31 13F GALLAGHER ARTHUR J COM 363576109 0 -33,597 -100.00 0 -100.00
2020-10-07 2020-09-30 13F GALLAGHER ARTHUR J COM 363576109 33,597 25,587 319.44 3,547 354.16 0.0199
2020-07-21 2020-06-30 13F GALLAGHER ARTHUR J COM 363576109 8,010 -11,197 -58.30 781 -50.13 0.0050
2020-04-17 2020-03-31 13F GALLAGHER ARTHUR J COM 363576109 19,207 -13,761 -41.74 1,566 -50.13 0.0125
2020-01-17 2019-12-31 13F GALLAGHER ARTHUR J COM 363576109 32,968 20,709 168.93 3,140 185.97 0.0197
2019-10-16 2019-09-30 13F GALLAGHER ARTHUR J COM 363576109 12,259 -43,221 -77.90 1,098 -77.40 0.0074
2019-08-12 2019-06-30 13F GALLAGHER ARTHUR J COM 363576109 55,480 2,704 5.12 4,859 17.88 0.0365
2019-04-26 2019-03-31 13F GALLAGHER ARTHUR J COM 363576109 52,776 42,476 412.39 4,122 443.08 0.0387
2019-01-23 2018-12-31 13F GALLAGHER ARTHUR J COM 363576109 10,300 -99,532 -90.62 759 -90.72 0.0086
2018-10-29 2018-09-30 13F GALLAGHER ARTHUR J COM 363576109 109,832 -64,828 -37.12 8,176 -28.29 0.0807
2018-07-17 2018-06-30 13F GALLAGHER ARTHUR J COM 363576109 174,660 74,502 74.38 11,402 65.63 0.1316
2018-04-30 2018-03-31 13F GALLAGHER ARTHUR J COM 363576109 100,158 92,841 1,268.84 6,884 1,386.83 0.0897
2018-01-25 2017-12-31 13F GALLAGHER ARTHUR J COM 363576109 7,317 7,317 463 0.0048
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.