Comparable stake leader
TCG Crossover GP II, LLC
SEC ownership of Alector, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001653087.
Disclosed value leader
TCG Crossover GP II, LLC
Comparable rows
50/50
Latest evidence
31 Mar 2026
- Public ticker
- ALEC on Nasdaq
- Parsed ownership sources
-
13D/G, 3/4/5, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
TCG Crossover GP II, LLC
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
50 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
TCG Crossover GP II, LLC
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
31 Mar 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001653087
- Issuer location
- South San Francisco, CA
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 Alector, Inc. (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
TCG Crossover GP II, LLC
Disclosed value leader
TCG Crossover GP II, LLC
Comparable rows
50/50
Latest evidence
31 Mar 2026
13D/G
3/4/5
13F
Lead comparable stake: 9.2%
13D/G row: TCG Crossover GP II, LLC
Showing 1-8 of 50 holder rows.
Quick read
TCG Crossover GP II, LLC leads the comparable SEC ownership view at 9.2%.
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 TCG Crossover GP II, LLC's linked filing trail.
Comparable ownership
Top 5
TCG Crossover GP II, LLC
9.2%
Arnon Rosenthal
7.4%
BlackRock, Inc.
5.2%
Polaris Venture Partners VI, L.P.
4.7%
FMR LLC
3.6%
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 |
|---|---|---|---|---|---|
| TCG Crossover GP II, LLC |
13D/G
Chen Yu
|
9.2%
|
$29,600,000
10,000,000 shares
|
$0 | 22 Oct 2025 |
| Arnon Rosenthal |
13D/G
3/4/5
Chief Executive Officer, Director
|
7.4%
|
$12,813,723
8,213,925 shares
|
$0 | 31 Dec 2025 |
| BlackRock, Inc. |
13F
13D/G
Company
|
5.2%
from 13D/G
|
$16,643,677
7,741,245 shares
|
— | 31 Mar 2026 |
| Polaris Venture Partners VI, L.P. |
13D/G
Terrance G. McGuire
|
4.7%
|
$12,157,723
5,173,499 shares
|
-$4,516,117 | 31 Mar 2026 |
| FMR LLC |
13D/G
13F
Company
|
3.6%
|
$10,655,467
3,599,820 shares
|
$0 | 31 Oct 2025 |
| Marc Grasso |
3/4/5
Chief Financial Officer
|
0.27%
|
$396,262
296,072 shares
|
— | 02 Jun 2025 |
| TCG Crossover Management, LLC |
13F
Company
|
9.1%
|
$21,500,000
10,000,000 shares
|
— | 31 Mar 2026 |
| ACADIAN ASSET MANAGEMENT LLC |
13F
Company
|
3.7%
|
$8,675,000
4,038,785 shares
|
— | 31 Mar 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: -$1,019,689.
Buys
$0
Insiders: 0
Sells
$1,019,689
Insiders: 5
Net
-$1,019,689
Shares: -561,850
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 561,850
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 126,764 | $0 | $250,861 | -$250,861 |
| 3-6 | 0 | 128,030 | $0 | $273,773 | -$273,773 |
| 6-9 | 0 | 196,104 | $0 | $219,987 | -$219,987 |
| 9-12 | 0 | 110,952 | $0 | $275,068 | -$275,068 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 22 reporting-owner rows connected to Alector, Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
22
Largest Forms 3/4/5 holder
Polaris Venture Management Co. VI, L.L.C.
Net 12M change
-$1,019,688
Latest report
17 Jun 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Polaris Venture Management Co. VI, L.L.C. | 10%+ Owner | $68,200,238 | Mixed | 29 May 2024 | ||
| Terrance McGuire | Director, 10%+ Owner | $60,653,001 | Mixed | 11 Sep 2023 | ||
| Tillman U. Gerngross | Director | $14,702,414 | Mixed | 14 Jun 2023 | ||
| Arnon Rosenthal | Chief Executive Officer, Director | $6,076,449 | -$591,579 | -8.9% | Mixed | 02 Jun 2026 |
| Robert King | Chief Development Officer | $3,062,843 | Mixed | 01 Oct 2022 | ||
| Robert Paul | Chief Medical Officer | $1,302,814 | Mixed | 09 Aug 2021 | ||
| Neil Lindsay Berkley | CFO & Chief Business Officer | $749,998 | -$182,446 | -20% | Filing P/S | 02 Jun 2026 |
| Shehnaaz Suliman | President and COO | $570,445 | Mixed | 10 Dec 2021 | ||
| Sara Kenkare-Mitra | President and Head of R&D | $561,649 | -$105,692 | -16% | Filing P/S | 03 Dec 2025 |
| David M. Wehner | Director | $553,434 | Mixed | 12 Jun 2024 | ||
| Gary Romano | Chief Medical Officer | $488,610 | Filing P/S | 03 Mar 2025 | ||
| Calvin Yu | Vice President, Finance | $426,374 | Mixed | 02 Jul 2021 | ||
| Marc Grasso | Chief Financial Officer | $396,262 | Filing P/S | 02 Jun 2025 | ||
| Louis J. Lavigne Jr. | Director | $298,120 | Mixed | 17 Jun 2026 | ||
| Richard H. Scheller | Director | $290,032 | Mixed | 17 Jun 2026 | ||
| Kristine Yaffe | Director | $266,834 | Mixed | 17 Jun 2026 | ||
| Elizabeth A. Garofalo | Director | $255,097 | Mixed | 17 Jun 2026 | ||
| Paula Hammond | Director | $222,759 | -$32,998 | -13% | Mixed | 17 Jun 2026 |
| Errol B. Desouza | Director | $212,097 | Mixed | 17 Jun 2026 | ||
| Mark Altmeyer | Director | $212,097 | Mixed | 17 Jun 2026 |
Recent insider transactions for Alector, Inc.
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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Kristine Yaffe | ALEC | Common Stock | Award | 30.1% | 28,700 | 124,109 | 17 Jun 2026 | Direct | ||
| Kristine Yaffe | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Richard H. Scheller | ALEC | Common Stock | Award | 27% | 28,700 | 134,899 | 17 Jun 2026 | Direct | ||
| Richard H. Scheller | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Paula Hammond | ALEC | Common Stock | Award | 38.3% | 28,700 | 103,609 | 17 Jun 2026 | Direct | ||
| Paula Hammond | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Elizabeth A. Garofalo | ALEC | Common Stock | Award | 31.9% | 28,700 | 118,650 | 17 Jun 2026 | Direct | ||
| Elizabeth A. Garofalo | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Mark Altmeyer | ALEC | Common Stock | Award | 41% | 28,700 | 98,650 | 17 Jun 2026 | Direct | ||
| Mark Altmeyer | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Errol B. Desouza | ALEC | Common Stock | Award | 41% | 28,700 | 98,650 | 17 Jun 2026 | Direct | ||
| Errol B. Desouza | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Louis J. Lavigne Jr. | ALEC | Common Stock | Award | 28.9% | 28,700 | 128,109 | 17 Jun 2026 | Direct | ||
| Louis J. Lavigne Jr. | ALEC | Stock Option (right to buy) | Award | 9,450 | 9,450 | 17 Jun 2026 | Direct | |||
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -3.51% | $6,543 | $1.88 | -3,475 | 95,461 | 03 Jun 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -3.51% | $6,543 | $1.88 | -3,475 | 95,461 | 03 Jun 2026 | Direct |
| Arnon Rosenthal | ALEC | Common Stock | Sale | -3.55% | $172,191 | $1.97 | -87,216 | 2,367,206 | 02 Jun 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -5.46% | $11,271 | $1.97 | -5,709 | 98,936 | 02 Jun 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -5.46% | $11,271 | $1.97 | -5,709 | 98,936 | 02 Jun 2026 | Direct |
| Neil Lindsay Berkley | ALEC | Common Stock | Sale | -4.85% | $38,221 | $1.97 | -19,360 | 379,900 | 02 Jun 2026 | Direct |
| Richard H. Scheller | ALEC | Common Stock | Award | 11.4% | 10,833 | 106,199 | 01 Jun 2026 | Direct | ||
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -1.71% | $4,823 | $2.65 | -1,820 | 104,645 | 16 Apr 2026 | Direct |
| Neil Lindsay Berkley | ALEC | Common Stock | Award | 15.8% | 54,600 | 399,260 | 15 Mar 2026 | Direct | ||
| Arnon Rosenthal | ALEC | Common Stock | Award | 4.97% | 116,246 | 2,454,422 | 13 Mar 2026 | Direct | ||
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -0.93% | $2,650 | $2.65 | -1,000 | 106,465 | 10 Mar 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -3.04% | $7,012 | $2.08 | -3,367 | 107,465 | 03 Mar 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -6.79% | $17,138 | $2.12 | -8,071 | 110,832 | 02 Mar 2026 | Direct |
| Arnon Rosenthal | ALEC | Common Stock | Sale | -3.38% | $173,822 | $2.12 | -81,864 | 2,338,176 | 02 Mar 2026 | Direct |
| Neil Lindsay Berkley | ALEC | Common Stock | Sale | -7.92% | $62,954 | $2.12 | -29,649 | 344,660 | 02 Mar 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -3.32% | $10,198 | $2.50 | -4,079 | 118,903 | 26 Feb 2026 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -3.72% | $5,751 | $1.21 | -4,753 | 122,982 | 05 Dec 2025 | Direct |
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -5.93% | $9,019 | $1.12 | -8,056 | 127,735 | 03 Dec 2025 | Direct |
| Arnon Rosenthal | ALEC | Common Stock | Sale | -4.13% | $116,827 | $1.12 | -104,347 | 2,420,040 | 03 Dec 2025 | Direct |
| Sara Kenkare-Mitra | ALEC | Common Stock | Sale | -7.67% | $46,673 | $1.12 | -41,687 | 501,652 | 03 Dec 2025 | Direct |
| Neil Lindsay Berkley | ALEC | Common Stock | Sale | -9.05% | $41,717 | $1.12 | -37,261 | 374,309 | 03 Dec 2025 | Direct |
| Neil Lindsay Berkley | ALEC | Common Stock | Award | 18.8% | 65,000 | 411,570 | 10 Nov 2025 | Direct | ||
| Neil Lindsay Berkley | ALEC | Employee Stock Option (right to buy) | Award | 195,000 | 195,000 | 10 Nov 2025 | Direct | |||
| Grace Wong-Sarad | ALEC | Common Stock | Award | 31.3% | 32,343 | 135,791 | 10 Nov 2025 | Direct | ||
| Grace Wong-Sarad | ALEC | Employee Stock Option (right to buy) | Award | 48,535 | 48,535 | 10 Nov 2025 | Direct | |||
| Arnon Rosenthal | ALEC | Common Stock | Award | 7.41% | 174,167 | 2,524,387 | 10 Nov 2025 | Direct | ||
| Arnon Rosenthal | ALEC | Employee Stock Option (right to buy) | Award | 522,500 | 522,500 | 10 Nov 2025 | Direct | |||
| Grace Wong-Sarad | ALEC | Common Stock | Sale | -5.4% | $14,756 | $2.50 | -5,910 | 103,448 | 02 Sep 2025 | Direct |
| Neil Lindsay Berkley | ALEC | Common Stock | Sale | -4.37% | $39,554 | $2.50 | -15,842 | 346,570 | 02 Sep 2025 | Direct |
| Sara Kenkare-Mitra | ALEC | Common Stock | Sale | -4.17% | $59,019 | $2.50 | -23,638 | 543,339 | 02 Sep 2025 | Direct |
| Arnon Rosenthal | ALEC | Common Stock | Sale | -2.15% | $128,740 | $2.50 | -51,562 | 2,350,220 | 02 Sep 2025 | Direct |
| Paula Hammond | ALEC | Common Stock | Sale | -15.8% | $32,998 | $2.36 | -14,000 | 74,909 | 26 Aug 2025 | Direct |
* marks a reported price that did not pass the local price check.