Polaris Venture Partners VI, L.P. - 30 Sep 2025 SCHEDULE 13G/A Report for Alector, Inc. Common Stock, $0.0001 par value per share (ALEC)

Filing manager
Polaris Venture Partners VI, L.P.
Reporting owner
Terrance G. McGuire
Security
Alector, Inc. Common Stock, $0.0001 par value per share
Beneficially owned shares
7,095,251 shares
Ownership signal CIK-linked ownership evidence from parsed SEC filings. 2 signals
Large-stake signal

Form

SCHEDULE 13G/A

Passive or exempt beneficial ownership filing.

Ownership

6.5%

Beneficial ownership of this reported class.

Shares

7,095,251 shares

Shares beneficially owned as disclosed.

Event date

30 Sep 2025

Date tied to the ownership event or amendment.

Accepted by SEC

13 Nov 2025

EDGAR acceptance date.

How to read this large-stake filing
  • Schedule 13D/G filings focus on beneficial ownership stakes, not a full portfolio.
  • Compare this filing with the holder history and issuer page before treating the percentage as a current position.
  • Use amendments to understand whether the disclosed stake increased, decreased, or changed reporting status.
Class ownership
6.5%
Subject security Names, identifiers, and filing context for this profile. 2 source fields
Symbol
ALEC
Shares outstanding
109,157,708 shares
Source evidence Original filing metadata and source links for verification. 5 source fields
SEC form
SCHEDULE 13G/A
Accepted by SEC
13 Nov 2025, 16:41:55 UTC
Event date
30 Sep 2025
Next SEC filing
14 May 2026
Source filing
View source filing

Key filing fact

Polaris Venture Partners VI, L.P. disclosed 6.5% ownership in Alector, Inc. Common Stock, $0.0001 par value per share (ALEC) on 30 Sep 2025.

Key facts

  • Polaris Venture Partners VI, L.P. filed SCHEDULE 13G/A for Alector, Inc. Common Stock, $0.0001 par value per share (ALEC).
  • Disclosed ownership: 6.5%.
  • Date of event: 30 Sep 2025.

Change

  • No earlier schedule filing is available for direct comparison.
  • Current filing was accepted on 13 Nov 2025, 16:41.

Research use

  • This page turns one Schedule 13D/G filing into a quick large-stake read before the raw reporting-person rows.
  • Use the linked SEC filing as the source of truth for ownership percentages, shares, and reporting-party details.

Evidence

Backed by Schedule 13D/13G

Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.

View source filing

Reporting persons

Disclosed reporting parties (11)

Names, ownership percentages, voting power, signatures, titles, and CIKs as disclosed in this Schedule 13D/G filing.

Name Ownership Shares owned Sole voting power Shared voting power Signature Title CIK
Polaris Venture Partners VI, L.P. 0.5% 498,468 498,468 0 /s/ Lauren Crockett Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., general partner of Polaris Venture Partners VI, L.P.
Polaris Venture Partners Founders' Fund VI, L.P. 0.3% 378,403 378,403 0 /s/ Lauren Crockett Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., GP of Polaris Venture Partners Founders' Fund VI, L.P.
Polaris Venture Partners VI (AIV), L.P. 4.4% 4,797,563 4,797,563 0 /s/ Lauren Crockett Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., general partner of Polaris Venture Partners VI (AIV), L.P.
Polaris Venture Partners VI (AIV-B), L.P. 1.1% 1,179,383 1,179,383 0 /s/ Lauren Crockett Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., general partner of Polaris Venture Partners VI (AIV-B), L.P.
Polaris Venture Management Co VI, L.L.C. 6.3% 6,853,817 0 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Authorized Signatory*
David Barrett 6.3% 6,880,071 26,254 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Attorney-In-Fact
Brian Chee 6.3% 6,880,084 26,267 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Attorney-In-Fact
Jonathan A. Flint 6.3% 6,892,942 39,125 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Attorney-In-Fact
Terrance G. McGuire 6.5% 7,095,251 241,434 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Attorney-In-Fact
Amir Nashat 6.4% 6,932,617 78,800 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Attorney-In-Fact
Bryce Youngren 6.4% 6,945,149 91,332 6,853,817 /s/ Lauren Crockett Lauren Crockett/ Attorney-In-Fact
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