SEI Investments Company
MX ˙ BMV ˙ US7841171033
SecurityMX:SEIC / SEI Investments Company
InstitutionAmerican Capital Management Inc
Latest Disclosed Ownership768,615 shares
Latest Disclosed Value $ 60,313,219
American Capital Management Inc reports 33.71% increase in ownership of SEIC / SEI Investments Company

On May 15, 2026 - American Capital Management Inc filed a 13F-HR form disclosing ownership of 768,615 shares of SEI Investments Company (MX:SEIC) valued at $60,313,219 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 574,819 shares of SEI Investments Company. This represents a change in shares of 33.71% 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)
2026-05-15 2026-03-31 13F SEI INVESTMENTS COM 784117103 768,615 193,796 33.71 60,313 27.93 3.2393
2026-02-17 2025-12-31 13F SEI INVESTMENTS COM 784117103 574,819 9,702 1.72 47,147 -1.68 2.0802
2025-11-14 2025-09-30 13F SEI INVESTMENTS COM 784117103 565,117 101,341 21.85 47,950 15.06 1.9103
2025-08-14 2025-06-30 13F SEI Investments COM 784117103 463,776 -57,130 -10.97 41,675 3.06 1.7286
2025-05-15 2025-03-31 13F SEI Investments COM 784117103 520,906 23,706 4.77 40,438 -1.39 1.6455
2025-02-11 2024-12-31 13F SEI Investments COM 784117103 497,200 192,814 63.35 41,009 94.72 1.5266
2024-11-14 2024-09-30 13F SEI Investments COM 784117103 304,386 62 0.02 21,060 6.98 0.6887
2024-08-14 2024-06-30 13F SEI Investments COM 784117103 304,324 -1,285 -0.42 19,687 -10.41 0.6590
2024-05-15 2024-03-31 13F SEI Investments COM 784117103 305,609 -1,339 -0.44 21,973 12.65 0.7043
2024-02-14 2023-12-31 13F SEI Investments COM 784117103 306,948 -10,289 -3.24 19,507 2.09 0.6672
2023-11-14 2023-09-30 13F SEI Investments COM 784117103 317,237 -50,170 -13.66 19,107 -12.77 0.7366
2023-08-14 2023-06-30 13F SEI Investments COM 784117103 367,407 -108,917 -22.87 21,905 -20.09 0.7607
2023-05-03 2023-03-31 13F SEI Investments COM 784117103 476,324 -1,745 -0.37 27,412 -1.65 0.9648
2023-02-14 2022-12-31 13F SEI Investments COM 784117103 478,069 -85,440 -15.16 27,871 0.84 1.0913
2022-11-14 2022-09-30 13F SEI Investments COM 784117103 563,509 -34,375 -5.75 27,640 -14.42 1.0910
2022-08-15 2022-06-30 13F SEI Investments COM 784117103 597,884 -108,438 -15.35 32,298 -24.05 1.2104
2022-05-16 2022-03-31 13F SEI Investments COM 784117103 706,322 -48,616 -6.44 42,528 -7.56 1.2541
2022-02-14 2021-12-31 13F SEI Investments COM 784117103 754,938 -1,831 -0.24 46,006 2.52 1.1812
2021-11-15 2021-09-30 13F SEI Investments COM 784117103 756,769 -17,482 -2.26 44,876 -6.47 1.2052
2021-08-13 2021-06-30 13F SEI Investments COM 784117103 774,251 -1,245 -0.16 47,980 1.54 1.3436
2021-05-17 2021-03-31 13F SEI Investments COM 784117103 775,496 -531 -0.07 47,251 5.95 1.4285
2021-02-16 2020-12-31 13F SEI Investments COM 784117103 776,027 5,401 0.70 44,598 14.10 1.3336
2020-11-16 2020-09-30 13F SEI Investments COM 784117103 770,626 -35,613 -4.42 39,086 -11.82 1.4363
2020-08-13 2020-06-30 13F SEI Investments COM 784117103 806,239 4,084 0.51 44,327 19.25 1.6302
2020-05-15 2020-03-31 13F SEI Investments COM 784117103 802,155 35,397 4.62 37,172 -25.96 1.8086
2020-02-12 2019-12-31 13F SEI Investments COM 784117103 766,758 7,640 1.01 50,207 11.62 2.1048
2019-11-14 2019-09-30 13F SEI Investments COM 784117103 759,118 -1,950 -0.26 44,982 5.35 1.9914
2019-11-14 2019-06-30 13F/A-1 SEI Investments COM 784117103 761,068 24,600 3.34 42,696 10.96 1.8269
2019-08-12 2019-06-30 13F SEI Investments COM 784117103 761,068 24,600 42,696
2019-05-14 2019-03-31 13F SEI Investments COM 784117103 736,468 1,850 0.25 38,480 13.38 1.7841
2019-02-08 2018-12-31 13F SEI Investments COM 784117103 734,618 -63,475 -7.95 33,939 -30.40 1.8115
2018-11-02 2018-09-30 13F SEI Investments COM 784117103 798,093 -67,355 -7.78 48,763 -9.88 2.1317
2018-07-17 2018-06-30 13F SEI Investments COM 784117103 865,448 11,135 1.30 54,108 -15.45 2.7939
2018-04-23 2018-03-31 13F SEI Investments COM 784117103 854,313 1,428 0.17 63,997 4.42 3.6458
2018-04-05 2017-12-31 13F/A-1 SEI Investments COM 784117103 852,885 6,995 0.83 61,288 18.66 3.6872
2018-01-23 2017-12-31 13F SEI Investments COM 784117103 856,885 10,995 61,576
2018-04-05 2017-09-30 13F/A-1 SEI Investments COM 784117103 845,890 6,370 0.76 51,650 14.40 3.2282
2017-10-20 2017-09-30 13F SEI Investments COM 784117103 849,780 4,620 51,888
2018-04-19 2017-06-30 13F/A-1 SEI Investments COM 784117103 839,520 13,760 1.67 45,149 8.40 2.9125
2017-07-27 2017-06-30 13F SEI Investments COM 784117103 845,160 19,400 45,453
2018-04-18 2017-03-31 13F/A-1 SEI Investments COM 784117103 825,760 9,135 1.12 41,651 3.33 2.9402
2017-04-24 2017-03-31 13F SEI Investments COM 784117103 827,530 10,905 41,741
2017-02-16 2016-12-31 13F/A-1 SEI Investments COM 784117103 816,625 100,420 14.02 40,309 23.40 3.1207
2017-02-09 2016-12-31 13F SEI Investments COM 784117103 816,625 40,309
2016-10-26 2016-09-30 13F SEI Investments COM 784117103 716,205 34,085 5.00 32,666 -0.46 2.5097
2016-08-03 2016-06-30 13F SEI Investments COM 078411710 682,120 1,540 0.23 32,817 12.01 2.7142
2016-04-25 2016-03-31 13F SEI Investments COM 784117103 680,580 12,340 1.85 29,299 -16.33 2.5586
2016-02-10 2015-12-31 13F SEI Investments COM 784117103 668,240 9,040 1.37 35,016 10.14 3.1078
2015-11-03 2015-09-30 13F SEI Investments COM 784117103 659,200 12,320 1.90 31,793 0.24 3.2964
2015-07-21 2015-06-30 13F SEI Investments COM 784117103 646,880 -21,710 -3.25 31,717 7.60 3.0206
2015-04-16 2015-03-31 13F/A-1 SEI Investments COM 784117103 682,190 16,070 30,078 2.9149
2015-04-21 2015-03-31 13F/A-2 SEI Investments COM 784117103 668,590 2,470 0.37 29,478 10.52 2.9001
2015-04-16 2015-03-31 13F SEI Investments COM 784117103 556,150 16,045
2015-02-06 2014-12-31 13F SEI Investments COM 784117103 666,120 -13,500 -1.99 26,671 8.53 2.8948
2014-10-14 2014-09-30 13F SEI Investments COM 784117103 679,620 0 0.00 24,575 10.35 2.8594
2014-07-16 2014-06-30 13F SEI Investments COM 784117103 679,620 83,570 14.02 22,271 11.17 2.5028
2014-04-14 2014-03-31 13F SEI Investments COM 784117103 596,050 5,850 0.99 20,033 -2.27 2.3613
2014-01-23 2013-12-31 13F SEI Investments COM 784117103 590,200 20,100 3.53 20,498 16.32 2.5400
2013-10-08 2013-09-30 13F SEI Investments COM 784117103 570,100 3,250 0.57 17,622 9.34 2.3662
2013-07-18 2013-06-30 13F SEI Investments COM 784117103 566,850 566,850 16,116 2.4199
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.