Comparable stake leader
LOOMIS SAYLES & CO L P
SEC ownership of SEI INVESTMENTS CO
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000350894.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
04 Aug 2026
- Public ticker
- SEIC on Nasdaq
- Parsed ownership sources
-
13D/G, 13F, and 3/4/5
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
LOOMIS SAYLES & CO L P
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
50 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
LOOMIS SAYLES & CO L P
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
04 Aug 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0000350894
- Issuer location
- Oaks, PA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of SEI INVESTMENTS CO (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
LOOMIS SAYLES & CO L P
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
04 Aug 2026
13D/G
13F
3/4/5
Lead comparable stake: 7%
13D/G row: LOOMIS SAYLES & CO L P
Showing 1-8 of 50 holder rows.
Quick read
LOOMIS SAYLES & CO L P leads the comparable SEC ownership view at 7%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens LOOMIS SAYLES & CO L P's linked filing trail.
Comparable ownership
Top 5
LOOMIS SAYLES & CO L P
7%
BlackRock, Inc.
6.8%
VANGUARD PORTFOLIO MANAGEMENT LLC
5%
Alfred P. West Jr.
5.7%
Carmen Romeo
1.3%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| LOOMIS SAYLES & CO L P |
13D/G
13F
Company
|
7%
|
$807,709,415
8,462,121 shares
|
-$21,132,535 | 30 Jun 2026 |
| BlackRock, Inc. |
13F
13D/G
Company
|
6.8%
from 13D/G
|
$870,744,969
9,927,545 shares
|
— | 30 Jun 2026 |
| VANGUARD PORTFOLIO MANAGEMENT LLC |
13F
13D/G
Company · Vanguard Portfolio Management
|
5%
from 13D/G
|
$538,611,498
6,140,822 shares
|
— | 30 Jun 2026 |
| Alfred P. West Jr. |
3/4/5
Chairman Emeritus
|
5.7%
|
$600,637,348
6,818,451 shares
|
-$12,009,290 | 26 Jun 2026 |
| Carmen Romeo |
3/4/5
Director
|
1.3%
|
$124,885,851
1,560,293 shares
|
-$420,050 | 30 Dec 2025 |
| William Doran |
3/4/5
Director
|
0.51%
|
$56,001,581
618,802 shares
|
-$1,039,450 | 09 Jun 2026 |
| Kathryn Mccarthy |
3/4/5
Director
|
0.06%
|
$8,063,616
77,883 shares
|
-$2,802,650 | 03 Aug 2026 |
| Philip McCabe |
3/4/5
Title: Executive Vice President, Head of SEI's Investment Managers business
|
0.05%
|
$6,030,546
57,623 shares
|
-$5,504,090 | 04 Aug 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$42,683,534.
Buys
$0
Insiders: 0
Sells
$42,683,534
Insiders: 10
Net
-$42,683,534
Shares: -476,549
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 476,549
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 172,332 | $0 | $16,749,299 | -$16,749,299 |
| 3-6 | 0 | 126,447 | $0 | $10,808,795 | -$10,808,795 |
| 6-9 | 0 | 127,770 | $0 | $10,879,440 | -$10,879,440 |
| 9-12 | 0 | 50,000 | $0 | $4,246,000 | -$4,246,000 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 25 reporting-owner rows connected to SEI INVESTMENTS CO. Open a relationship link for the CIK-to-CIK filing trail.
Rows
25
Largest Forms 3/4/5 holder
Alfred P. West Jr.
Net 12M change
-$42,683,534
Latest report
04 Aug 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Alfred P. West Jr. | Chairman Emeritus | $600,637,348 | -$12,009,290 | -2% | Filing P/S | 26 Jun 2026 |
| Carmen Romeo | Director | $124,885,851 | -$420,050 | -0.34% | Mixed | 30 Dec 2025 |
| William Doran | Director | $56,001,581 | -$1,039,450 | -1.8% | Filing P/S | 09 Jun 2026 |
| Dennis McGonigle | Evp, Cfo | $20,058,943 | Mixed | 30 Aug 2023 | ||
| Ryan Hicke | CHIEF EXECUTIVE OFFICER, Director | $17,058,728 | -$6,989,060 | -29% | Mixed | 31 Mar 2026 |
| Kathryn Mccarthy | Director | $8,063,616 | -$2,802,650 | -26% | Filing P/S | 03 Aug 2026 |
| Kevin Barr | Executive Vice President | $6,912,056 | Mixed | 10 Dec 2021 | ||
| Philip McCabe | Title: Executive Vice President, Head of SEI's Investment Managers business | $6,030,546 | -$5,504,090 | -48% | Mixed | 04 Aug 2026 |
| Sean Denham | Executive VP, CFO, COO | $4,803,407 | Mixed | 18 Mar 2026 | ||
| Sanjay Sharma | Officer | $4,188,951 | -$4,239,601 | -50% | Mixed | 24 Jul 2026 |
| Wayne Withrow | Executive Vice President | $4,004,164 | Mixed | 07 Feb 2024 | ||
| Michael Lane | Executive Vice President | $3,376,556 | Mixed | 12 Dec 2025 | ||
| Paul Klauder | Executive Vice President | $2,431,134 | Mixed | 08 Mar 2024 | ||
| Michael Peterson | Executive Vice President | $2,087,880 | -$5,556,500 | -73% | Mixed | 28 Jul 2026 |
| Carl Guarino | Director | $1,889,294 | -$1,896,050 | -50% | Filing P/S | 28 Jul 2026 |
| James Cipriano | Executive Vice President | $1,889,055 | Mixed | 29 Feb 2024 | ||
| Sneha S. Shah | Title: EVP &Chief AI Strategist & Head of SEI Next | $1,255,354 | Median | 24 Jul 2026 | ||
| Jonathan Brassington | Director | $496,808 | Mixed | 12 Dec 2025 | ||
| Stephen Meyer | Executive Vice President | $394,250 | Mixed | 10 Dec 2021 | ||
| Thomas C. Naratil | Director | $347,533 | Mixed | 12 Dec 2025 |
Recent insider transactions for SEI INVESTMENTS CO
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Philip McCabe | SEIC | Common Stock | Sale | -8.42% | $532,036 | $105.50 | -5,043 | 54,884 | 05 Aug 2026 | Direct |
| Philip McCabe | SEIC | Common Stock | Options Exercise | 9.19% | 5,043 | 59,927 | 05 Aug 2026 | Direct | ||
| Philip McCabe | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -5,043 | 0 | 05 Aug 2026 | Direct | ||
| Philip McCabe | SEIC | Common Stock | Sale | -31.3% | $2,621,433 | $105.04 | -24,957 | 54,884 | 04 Aug 2026 | Direct |
| Philip McCabe | SEIC | Common Stock | Options Exercise | 45.5% | 24,957 | 79,841 | 04 Aug 2026 | Direct | ||
| Philip McCabe | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -24,957 | 0 | 04 Aug 2026 | Direct | ||
| Kathryn Mccarthy | SEIC | Common Stock | Sale | -11.4% | $1,035,350 | $103.54 | -10,000 | 77,883 | 03 Aug 2026 | Direct |
| Kathryn Mccarthy | SEIC | Common Stock | Options Exercise | 12.8% | 10,000 | 87,883 | 03 Aug 2026 | Direct | ||
| Kathryn Mccarthy | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -5,000 | 0 | 03 Aug 2026 | Direct | ||
| Mark Andrew Warner | SEIC | Common Stock | Sale | -94.2% | $1,535,193 | $102.35 | -15,000 | 921 | 28 Jul 2026 | Direct |
| Mark Andrew Warner | SEIC | Common Stock | Options Exercise | 1628.7% | 15,000 | 15,921 | 28 Jul 2026 | Direct | ||
| Mark Andrew Warner | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -7,500 | 0 | 28 Jul 2026 | Direct | ||
| Michael Peterson | SEIC | Common Stock | Sale | -55.4% | $2,551,250 | $102.05 | -25,000 | 20,148 | 28 Jul 2026 | Direct |
| Michael Peterson | SEIC | Common Stock | Options Exercise | 124.1% | 25,000 | 45,148 | 28 Jul 2026 | Direct | ||
| Michael Peterson | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -25,000 | 0 | 28 Jul 2026 | Direct | ||
| Carl Guarino | SEIC | Common Stock | Sale | -35.3% | $1,031,950 | $103.20 | -10,000 | 18,308 | 28 Jul 2026 | Direct |
| Carl Guarino | SEIC | Common Stock | Options Exercise | 54.6% | 10,000 | 28,308 | 28 Jul 2026 | Direct | ||
| Carl Guarino | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -5,000 | 0 | 28 Jul 2026 | Direct | ||
| Sanjay Sharma | SEIC | Common Stock | Sale | -33.4% | $1,986,588 | $99.33 | -20,000 | 39,829 | 24 Jul 2026 | Direct |
| Sanjay Sharma | SEIC | Common Stock | Options Exercise | 50.2% | 20,000 | 59,829 | 24 Jul 2026 | Direct | ||
| Sanjay Sharma | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -10,000 | 0 | 24 Jul 2026 | Direct | ||
| Sneha S. Shah | SEIC | Common Stock | Tax liability | -21% | -3,746 | 14,092 | 24 Jul 2026 | Direct | ||
| Alfred P. West Jr. | SEIC | Common Stock | Sale | -0.11% | $640,733 | $87.39 | -7,332 | 6,818,451 | 29 Jun 2026 | Direct |
| Alfred P. West Jr. | SEIC | Common Stock | Sale | -0.73% | $4,362,265 | $87.25 | -50,000 | 6,825,783 | 26 Jun 2026 | Direct |
| William Doran | SEIC | Common Stock | Sale | -0.8% | $452,500 | $90.50 | -5,000 | 618,802 | 09 Jun 2026 | Direct |
| Kathryn Mccarthy | SEIC | Common Stock | Sale | -11.4% | $910,700 | $91.07 | -10,000 | 77,883 | 04 May 2026 | Direct |
| Kathryn Mccarthy | SEIC | Common Stock | Options Exercise | 12.8% | 10,000 | 87,883 | 04 May 2026 | Direct | ||
| Kathryn Mccarthy | SEIC | STOCK OPTION (RIGHT TO PURCHASE) | Options Exercise | -100% | -5,000 | 0 | 04 May 2026 | Direct | ||
| Mark Andrew Warner | SEIC | Common Stock | Sale | -81.3% | $364,640 | $91.16 | -4,000 | 921 | 28 Apr 2026 | Direct |
| Mark Andrew Warner | SEIC | Common Stock | Options Exercise | 434.3% | 4,000 | 4,921 | 28 Apr 2026 | Direct | ||
| Mark Andrew Warner | SEIC | STOCK OPTION RIGHT TO PURCHASE | Options Exercise | -100% | -2,000 | 0 | 28 Apr 2026 | Direct | ||
| Philip McCabe | SEIC | Common Stock | Sale | -21.5% | $1,377,300 | $91.82 | -15,000 | 54,884 | 23 Apr 2026 | Direct |
| Sanjay Sharma | SEIC | Common Stock | Sale | -38.6% | $2,253,013 | $90.12 | -25,000 | 39,829 | 23 Apr 2026 | Direct |
| Sanjay Sharma | SEIC | Common Stock | Options Exercise | 62.8% | 25,000 | 64,829 | 23 Apr 2026 | Direct | ||
| Sanjay Sharma | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -12,500 | 0 | 23 Apr 2026 | Direct | ||
| Michael Peterson | SEIC | Common Stock | Sale | -33.2% | $900,000 | $90.00 | -10,000 | 20,148 | 23 Apr 2026 | Direct |
| Michael Peterson | SEIC | Common Stock | Options Exercise | 49.6% | 10,000 | 30,148 | 23 Apr 2026 | Direct | ||
| Michael Peterson | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -10,000 | 0 | 23 Apr 2026 | Direct | ||
| Sean Denham | SEIC | Common Stock | Tax liability | -11.7% | -7,673 | 57,758 | 18 Mar 2026 | Direct | ||
| Alfred P. West Jr. | SEIC | Common Stock | Sale | -0.11% | $590,270 | $79.26 | -7,447 | 6,875,783 | 11 Mar 2026 | Direct |
| Alfred P. West Jr. | SEIC | Common Stock | Sale | -0.79% | $4,412,871 | $80.23 | -55,000 | 6,883,230 | 10 Mar 2026 | Direct |
| Mark Andrew Warner | SEIC | Common Stock | Sale | -81.3% | $326,960 | $81.74 | -4,000 | 921 | 25 Feb 2026 | Direct |
| Mark Andrew Warner | SEIC | Common Stock | Award | 434.3% | 4,000 | 4,921 | 25 Feb 2026 | Direct | ||
| Mark Andrew Warner | SEIC | STOCK OPTION RIGHT TO PURCHASE | Options Exercise | -100% | -4,000 | 0 | 25 Feb 2026 | Direct | ||
| Ryan Hicke | SEIC | Common Stock | Sale | -28.9% | $6,989,060 | $87.36 | -80,000 | 197,164 | 29 Jan 2026 | Direct |
| Ryan Hicke | SEIC | Common Stock | Options Exercise | 40.6% | 80,000 | 277,164 | 29 Jan 2026 | Direct | ||
| Ryan Hicke | SEIC | Option to Purchase Common Stock | Options Exercise | -100% | -80,000 | 0 | 29 Jan 2026 | Direct | ||
| Alfred P. West Jr. | SEIC | Common Stock | Tax liability | -0.05% | -3,482 | 6,938,230 | 01 Jan 2026 | Direct | ||
| Carmen Romeo | SEIC | COMMON STOCK | Gift | -0.98% | -15,500 | 1,560,293 | 30 Dec 2025 | Direct | ||
| William Doran | SEIC | Common Stock | Sale | -1.11% | $586,950 | $83.85 | -7,000 | 623,802 | 22 Dec 2025 | Direct |
* marks a reported price that did not pass the local price check.