SEI Investments Company
MX ˙ BMV ˙ US7841171033
SecurityMX:SEIC / SEI Investments Company
InstitutionLord, Abbett & Co. Llc
Latest Disclosed Ownership2,204,379 shares
Latest Disclosed Value $ 172,978
Lord, Abbett & Co. Llc reports 14.97% increase in ownership of SEIC / SEI Investments Company

On May 14, 2026 - Lord, Abbett & Co. Llc filed a 13F-HR form disclosing ownership of 2,204,379 shares of SEI Investments Company (MX:SEIC) valued at $172,978 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 1,917,370 shares of SEI Investments Company. This represents a change in shares of 14.97% 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)
2026-05-14 2026-03-31 13F SEI INVTS COM 784117103 2,204,379 287,009 14.97 173 9.55 0.5647
2026-02-13 2025-12-31 13F SEI INVTS COM 784117103 1,917,370 308,988 19.21 157 15.44 0.4824
2025-11-13 2025-09-30 13F SEI INVTS COM 784117103 1,608,382 125,533 8.47 136 2.26 0.4063
2025-08-14 2025-06-30 13F SEI INVTS COM 784117103 1,482,849 815,931 122.34 133 160.78 0.4287
2025-05-13 2025-03-31 13F SEI INVTS COM 784117103 666,918 666,918 52 0.1844
2018-08-14 2018-06-30 13F SEI INVESTMENTS CO COM COM 784117103 0 -194,167 -100.00 0 -100.00
2018-05-15 2018-03-31 13F SEI INVESTMENTS CO COM COM 784117103 194,167 -111 -0.06 14,545 4.18 0.0432
2018-02-14 2017-12-31 13F SEI INVESTMENTS CO COM COM 784117103 194,278 93,778 93.31 13,961 127.49 0.0397
2017-11-14 2017-09-30 13F SEI INVESTMENTS CO COM COM 784117103 100,500 -152,400 -60.26 6,137 -54.88 0.0179
2017-08-24 2017-06-30 13F/A-1 SEI INVESTMENTS CO COM COM 784117103 252,900 29,700 13.31 13,601 20.81 0.0404
2017-08-14 2017-06-30 13F SEI INVESTMENTS CO COM COM 784117103 252,900 29,700 13,601
2017-05-15 2017-03-31 13F SEI INVESTMENTS CO COM COM 784117103 223,200 -73,800 -24.85 11,258 -23.21 0.0337
2017-02-14 2016-12-31 13F SEI INVESTMENTS CO COM COM 784117103 297,000 2,100 0.71 14,660 9.00 0.0445
2016-11-10 2016-09-30 13F SEI INVESTMENTS CO COM COM 784117103 294,900 116,700 65.49 13,450 56.89 0.0410
2016-08-12 2016-06-30 13F SEI INVESTMENTS CO COM COM 784117103 178,200 -77,100 -30.20 8,573 -22.00 0.0268
2016-05-16 2016-03-31 13F SEI INVESTMENTS CO COM COM 784117103 255,300 70,600 38.22 10,991 13.57 0.0346
2016-02-16 2015-12-31 13F SEI INVESTMENTS CO COM COM 784117103 184,700 184,700 0.00 9,678 0.0291
2015-08-14 2015-06-30 13F SEI INVESTMENTS CO COM COM 784117103 0 -95,735 -100.00 0 -100.00
2015-05-15 2015-03-31 13F SEI INVESTMENTS CO COM COM 784117103 95,735 -700 -0.73 4,221 9.32 0.0107
2015-02-13 2014-12-31 13F SEI Investments COM 784117103 96,435 -2,500 -2.53 3,861 7.94 0.0098
2014-11-14 2014-09-30 13F SEI Investments COM 784117103 98,935 18,600 23.15 3,577 35.85 0.0090
2014-08-20 2014-06-30 13F/A-1 SEI INVESTMENTS CO COM COM 784117103 80,335 -11,500 -12.52 2,633 -14.71 0.0060
2014-08-14 2014-06-30 13F SEI INVESTMENTS CO COM COM 784117103 80,335 2,633
2014-05-15 2014-03-31 13F SEI INVESTMENTS COM 784117103 91,835 -1,900 -2.03 3,087 -5.16 0.0070
2014-03-05 2013-12-31 13F/A-1 SEI Investments COM 784117103 93,735 5,100 5.75 3,255 18.80 0.0072
2014-02-14 2013-12-31 13F SEI Investments COM 784117103 93,735 3,255
2013-11-14 2013-09-30 13F SEI Investments COM 784117103 88,635 1,700 1.96 2,740 10.84 0.0063
2013-08-14 2013-06-30 13F SEI Investments COM 784117103 86,935 86,935 2,472 0.0057
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.