Arthur J. Gallagher & Co.
MX ˙ BMV ˙ US3635761097
SecurityMX:AJG / Arthur J. Gallagher & Co.
InstitutionRobeco Institutional Asset Management B.V.
Latest Disclosed Ownership4,543 shares
Latest Disclosed Value $ 983,924
Robeco Institutional Asset Management B.V. reports 5.33% decrease in ownership of AJG / Arthur J. Gallagher & Co.

On April 21, 2026 - Robeco Institutional Asset Management B.V. filed a 13F-HR form disclosing ownership of 4,543 shares of Arthur J. Gallagher & Co. (MX:AJG) valued at $983,924 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 4,799 shares of Arthur J. Gallagher & Co.. This represents a change in shares of -5.33% 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)
2026-04-21 2026-03-31 13F GALLAGHER ARTHUR J COM 363576109 4,543 -256 -5.33 984 -20.79 0.0014
2026-01-23 2025-12-31 13F GALLAGHER ARTHUR J COM 363576109 4,799 -4,955 -50.80 1,242 -58.92 0.0018
2025-10-22 2025-09-30 13F GALLAGHER ARTHUR J COM 363576109 9,754 -149 -1.50 3,021 -4.70 0.0044
2025-07-18 2025-06-30 13F GALLAGHER ARTHUR J COM 363576109 9,903 -2,788 -21.97 3,170 -27.64 0.0051
2025-04-23 2025-03-31 13F GALLAGHER ARTHUR J COM 363576109 12,691 -6,341 -33.32 4,381 -18.90 0.0085
2025-01-23 2024-12-31 13F GALLAGHER ARTHUR J COM 363576109 19,032 -40,096 -67.81 5,402 -67.53 0.0102
2024-10-29 2024-09-30 13F GALLAGHER ARTHUR J COM 363576109 59,128 -7,465 -11.21 16,637 -3.66 0.0330
2024-07-23 2024-06-30 13F GALLAGHER ARTHUR J COM 363576109 66,593 -12,350 -15.64 17,268 -12.51 0.0372
2024-04-24 2024-03-31 13F GALLAGHER ARTHUR J COM 363576109 78,943 -35,826 -31.22 19,739 -23.52 0.0429
2024-02-14 2023-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 114,769 24,261 26.81 25,809 25.11 0.0626
2024-02-08 2023-12-31 13F GALLAGHER ARTHUR J COM 363576109 58,141 -32,367 115 0.0215
2023-10-24 2023-09-30 13F GALLAGHER ARTHUR J COM 363576109 90,508 15,742 21.06 20,629 25.66 0.0551
2023-07-24 2023-06-30 13F GALLAGHER ARTHUR J COM 363576109 74,766 -3,849 -4.90 16,416 9.16 0.0430
2023-05-04 2023-03-31 13F GALLAGHER ARTHUR J COM 363576109 78,615 -31,851 -28.83 15,040 -27.79 0.0410
2023-02-07 2022-12-31 13F GALLAGHER ARTHUR J COM 363576109 110,466 -94,397 -46.08 20,827 -40.62 0.0600
2022-12-01 2022-09-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 204,863 -29,887 -12.73 35,076 -8.36 0.1133
2022-10-27 2022-09-30 13F GALLAGHER ARTHUR J COM 363576109 204,863 -29,887 35,076 0.1118
2022-12-01 2022-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 234,750 -55,575 -19.14 38,275 -24.49 0.1189
2022-07-27 2022-06-30 13F GALLAGHER ARTHUR J COM 363576109 234,750 -55,575 38,275 0.1173
2022-12-01 2022-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 290,325 -50,556 -14.83 50,692 -12.36 0.1194
2022-04-26 2022-03-31 13F GALLAGHER ARTHUR J COM 363576109 290,325 -50,556 50,692 0.1180
2022-12-01 2021-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 340,881 -150,649 -30.65 57,841 -20.84 0.1231
2022-01-31 2021-12-31 13F GALLAGHER ARTHUR J COM 363576109 340,881 -150,649 57,841 0.1216
2022-12-01 2021-09-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 491,530 -15,729 -3.10 73,064 2.83 0.1620
2021-10-20 2021-09-30 13F GALLAGHER ARTHUR J COM 363576109 491,530 -15,729 73,064 0.1599
2022-12-01 2021-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 507,259 324,344 177.32 71,055 211.33 0.1575
2021-07-28 2021-06-30 13F GALLAGHER ARTHUR J COM 363576109 507,259 324,344 71,055 0.1554
2022-12-01 2021-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 182,915 -95,860 -34.39 22,823 -33.82 0.0562
2021-04-23 2021-03-31 13F GALLAGHER ARTHUR J COM 363576109 182,915 -95,860 22,823 0.0555
2022-12-01 2020-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 278,775 28,143 11.23 34,487 30.32 0.0906
2021-01-28 2020-12-31 13F GALLAGHER ARTHUR J COM 363576109 278,775 28,143 34,487 0.0895
2021-01-19 2020-09-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 250,632 45,585 22.23 26,463 32.39 0.0818
2020-10-29 2020-09-30 13F GALLAGHER ARTHUR J COM 363576109 250,632 45,585 26,463 81,726.3566
2021-01-19 2020-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 205,047 -13,510 -6.18 19,989 12.20 0.0679
2020-07-20 2020-06-30 13F GALLAGHER ARTHUR J COM 363576109 205,047 -13,510 19,989 67,826.2424
2021-01-19 2020-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 218,557 -20,973 -8.76 17,815 -21.90 0.0715
2020-04-30 2020-03-31 13F GALLAGHER ARTHUR J COM 363576109 218,557 -20,973 17,815 71,406.5376
2021-01-19 2019-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 239,530 83,518 53.53 22,810 63.23 0.0730
2020-02-06 2019-12-31 13F GALLAGHER ARTHUR J COM 363576109 239,530 83,518 22,810 72,956.0309
2021-01-19 2019-09-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 156,012 76,048 95.10 13,974 99.54 0.0493
2019-10-17 2019-09-30 13F GALLAGHER ARTHUR J COM 363576109 156,012 76,048 13,974 49,264.0968
2021-01-19 2019-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 79,964 3,625 4.75 7,003 17.48 0.0247
2019-07-19 2019-06-30 13F GALLAGHER ARTHUR J COM 363576109 79,964 3,625 7,003 24,694.4098
2021-01-19 2019-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 76,339 1,200 1.60 5,961 7.64 0.0219
2019-05-02 2019-03-31 13F GALLAGHER ARTHUR J COM 363576109 76,339 1,200 5,961 21,886.6715
2021-01-19 2018-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 75,139 4,530 6.42 5,538 5.39 0.0249
2019-02-08 2018-12-31 13F GALLAGHER ARTHUR J COM 363576109 75,139 4,530 5,538 24,823.8106
2021-01-19 2018-09-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 70,609 0 0.00 5,255 14.02 0.0208
2018-10-25 2018-09-30 13F GALLAGHER ARTHUR J COM 363576109 70,609 0 5,255
2021-01-19 2018-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 70,609 -10,744 -13.21 4,609 -17.56 0.0210
2018-08-03 2018-06-30 13F GALLAGHER ARTHUR J COM 363576109 70,609 -10,744 4,609
2021-01-19 2018-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 81,353 6,878 9.24 5,591 18.65 0.0262
2018-05-07 2018-03-31 13F GALLAGHER ARTHUR J COM 363576109 81,353 6,878 5,591 26,146.4916
2021-01-19 2017-12-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 74,475 16,608 28.70 4,712 32.32 0.0244
2018-01-25 2017-12-31 13F GALLAGHER ARTHUR J COM 363576109 74,475 16,608 4,712
2021-01-19 2017-09-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 57,867 0 0.00 3,561 7.52 0.0221
2017-10-17 2017-09-30 13F GALLAGHER ARTHUR J COM 363576109 57,867 0 3,561 22,061.6442
2021-01-19 2017-06-30 13F/A-1 GALLAGHER ARTHUR J COM 363576109 57,867 0 0.00 3,312 1.25 0.0213
2017-08-07 2017-06-30 13F GALLAGHER ARTHUR J COM 363576109 57,867 0 3,312 21,563.7874
2021-01-19 2017-03-31 13F/A-1 GALLAGHER ARTHUR J COM 363576109 57,867 0 0.00 3,271 8.78 0.0218
2017-05-15 2017-03-31 13F GALLAGHER ARTHUR J COM 363576109 57,867 0 3,271 21,725.7845
2017-02-09 2016-12-31 13F GALLAGHER ARTHUR J COM 363576109 57,867 -7,051 -10.86 3,007 -8.96 0.0235
2016-11-07 2016-09-30 13F GALLAGHER ARTHUR J COM 363576109 64,918 0 0.00 3,303 6.89 0.0244
2016-07-22 2016-06-30 13F GALLAGHER ARTHUR J COM 363576109 64,918 -5,727 -8.11 3,090 -6.82 0.0234
2014-02-04 2013-12-31 13F GALLAGHER ARTHUR J COM 363576109 70,645 0 0.00 3,316 7.56 0.0276
2013-11-12 2013-09-30 13F GALLAGHER ARTHUR J COM 363576109 70,645 0 0.00 3,083 -0.10 0.0300
2013-08-27 2013-06-30 13F Arthur J Gallagher COM 363576109 70,645 70,645 3,086 0.0312
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.