Affiliated Managers Group, Inc.
US ˙ NYSE ˙ US0082521081

SecurityAMG / Affiliated Managers Group, Inc.
InstitutionSei Investments Co
Latest Disclosed Ownership102,297 shares
Latest Disclosed Value $ 29,488,960
Sei Investments Co reports 4.52% increase in ownership of AMG / Affiliated Managers Group, Inc.

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 102,297 shares of Affiliated Managers Group, Inc. (US:AMG) valued at $29,490,179 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 97,874 shares of Affiliated Managers Group, Inc.. This represents a change in shares of 4.52% during the quarter. The current value of the position is $31,876,768 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.

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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)
2026-02-13 2025-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 102,297 4,423 4.52 29,489 26.36 0.0291
2025-11-13 2025-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 97,874 37,202 61.32 23,337 95.49 0.0251
2025-08-14 2025-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 60,672 12,006 24.67 11,938 45.99 0.0138
2025-05-14 2025-03-31 13F/A-1 AFFILIATED MANAGERS GROUP IN COM 008252108 48,666 1,147 2.41 8,177 -6.93 0.0105
2025-05-13 2025-03-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 48,423 904 8,450 0.0092
2025-02-11 2024-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 47,519 -18,070 -27.55 8,787 -24.65 0.0113
2024-11-12 2024-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 65,589 20,457 45.33 11,662 65.40 0.0151
2024-08-13 2024-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 45,132 -3,053 -6.34 7,051 -12.62 0.0100
2024-05-07 2024-03-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 48,185 13,968 40.82 8,069 55.72 0.0118
2024-02-14 2023-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 34,217 -6,331 -15.61 5,181 -1.93 0.0083
2023-11-14 2023-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 40,548 -2,460 -5.72 5,284 -18.04 0.0095
2023-08-11 2023-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 43,008 692 1.64 6,447 6.97 0.0112
2023-05-12 2023-03-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 42,316 10,769 34.14 6,026 20.57 0.0112
2023-02-10 2022-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 31,547 424 1.36 4,998 43.58 0.0111
2022-11-14 2022-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 31,123 31,123 3,481 0.0078
2022-08-15 2022-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 0 -2,966 -100.00 0 -100.00
2022-05-13 2022-03-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 2,966 -4,821 -61.91 368 -68.79 0.0007
2022-02-14 2021-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 7,787 -4,492 -36.58 1,179 -33.91 0.0022
2021-11-12 2021-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 12,279 -6,824 -35.72 1,784 -37.99 0.0037
2021-08-06 2021-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 19,103 19,103 2,877 0.0064
2021-02-08 2020-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 0 -3,328 -100.00 0 -100.00
2020-12-04 2020-09-30 13F/A-1 AFFILIATED MANAGERS GROUP IN COM 008252108 3,328 -61 -1.80 216 -17.24 0.0006
2020-11-06 2020-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 3,435 46 223 536.9344
2020-08-11 2020-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 3,389 3,389 1.83 261 20.83 0.0008
2020-05-14 2020-03-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 0 -3,505 -100.00 0 -100.00
2020-02-06 2019-12-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 3,505 -2,680 -43.33 302 -41.92 0.0009
2019-11-12 2019-09-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 6,185 -17,564 -73.96 520 -76.23 0.0013
2019-08-14 2019-06-30 13F AFFILIATED MANAGERS GROUP IN COM 008252108 23,749 -128,866 -84.44 2,188 -86.60 0.0071
2019-05-15 2019-03-31 13F AFFILIATED MANAGERS GROUP IN COM 008252108 152,615 35,318 30.11 16,331 2.18 0.0548
2019-02-13 2018-12-31 13F AFFILIATED MANAGERS GROUP COM 008252108 117,297 -4,355 -3.58 15,983 -3.84 0.0569
2018-11-08 2018-09-30 13F AFFILIATED MANAGERS GROUP COM 008252108 121,652 21,393 21.34 16,622 11.52 0.0602
2018-08-03 2018-06-30 13F AFFILIATED MANAGERS GROUP COM 008252108 100,259 93,342 1,349.46 14,905 1,036.05 0.0507
2018-05-11 2018-03-31 13F AFFILIATED MANAGERS GROUP COM 008252108 6,917 -112,832 -94.22 1,312 -94.66 0.0050
2018-02-08 2017-12-31 13F AFFILIATED MANAGERS GROUP COM 008252108 119,749 -113 -0.09 24,578 8.02 0.0853
2017-11-06 2017-09-30 13F AFFILIATED MANAGERS GROUP COM 008252108 119,862 -2,226 -1.82 22,753 12.37 0.0809
2017-07-31 2017-06-30 13F AFFILIATED MANAGERS GROUP COM 008252108 122,088 10,240 9.16 20,249 10.43 0.0807
2017-05-05 2017-03-31 13F AFFILIATED MANAGERS GROUP COM 008252108 111,848 21,302 23.53 18,336 39.37 0.0804
2017-02-02 2016-12-31 13F AFFILIATED MANAGERS GROUP COM 008252108 90,546 5,041 5.90 13,156 6.33 0.0637
2016-11-04 2016-09-30 13F AFFILIATED MANAGERS GROUP COM 008252108 85,505 1,272 1.51 12,373 4.34 0.0629
2016-08-11 2016-06-30 13F AFFILIATED MANAGERS GROUP COM 008252108 84,233 2,076 2.53 11,858 -11.12 0.0711
2016-05-10 2016-03-31 13F/A-1 AFFILIATED MANAGERS GROUP COM 008252108 82,157 9,193 12.60 13,342 14.45 0.0830
2016-02-03 2015-12-31 13F AFFILIATED MANAGERS GROUP COM 008252108 72,964 43,382 146.65 11,657 130.42 0.0710
2015-11-02 2015-09-30 13F/A-1 AFFILIATED MANAGERS GROUP COM 008252108 29,582 -8,054 -21.40 5,059 -38.51 0.0464
2015-10-30 2015-09-30 13F AFFILIATED MANAGERS GROUP COM 008252108 29,582 5,059
2015-08-07 2015-06-30 13F/A-1 AFFILIATED MANAGERS GROUP COM 008252108 37,636 -19,265 -33.86 8,227 -32.69 0.0744
2015-08-04 2015-06-30 13F AFFILIATED MANAGERS GROUP COM 008252108 37,636 -19,265 8,227 0.0744
2015-05-14 2015-03-31 13F/A-1 AFFILIATED MANAGERS GROUP COM 008252108 56,901 -67,076 -54.10 12,223 -53.55 0.1061
2015-05-01 2015-03-31 13F AFFILIATED MANAGERS GROUP COM 008252108 56,901 12,223
2015-02-10 2014-12-31 13F AFFILIATED MANAGERS GROUP COM 008252108 123,977 123,977 26,315 0.2326
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.