Arnon Rosenthal - 10 Nov 2025 Form 4 Insider Report for Alector, Inc. (ALEC)

Reporting relationship: Chief Executive Officer, Director
Issuer ticker: ALEC
Reported as of: 10 Nov 2025
Net transaction value: $0
SEC form: 4
Accepted by SEC: 12 Nov 2025, 16:10:27 UTC
Prior SEC filing: 04 Sep 2025
Next SEC filing: 03 Dec 2025
Source filing: View source filing
Reporting owner signature: /s/ Grace Wong-Sarad, by power of attorney

Key filing fact

Arnon Rosenthal filed Form 4 for Alector, Inc. (ALEC) on 12 Nov 2025.

Key facts

This page summarizes Arnon Rosenthal's Form 4 filing for Alector, Inc. (ALEC).
2 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 12 Nov 2025, 16:10.

Change

Previous filing in this sequence was filed on 04 Sep 2025.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001757770 Primary reporting owner

Rosenthal Arnon

Relationship: Chief Executive Officer, Director
Address: C/O ALECTOR, INC., 131 OYSTER POINT BLVD, SUITE 600, SOUTH SAN FRANCISCO
Signature: /s/ Grace Wong-Sarad, by power of attorney
Signature date: 12 Nov 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

ALEC transaction

Common Stock

Award

Transaction value: $0
Shares: +174,167
Change %: +7.4%
Price: $0.000000
Shares after: 2,524,387
Date: 10 Nov 2025
Ownership: Direct
Footnotes: F1

ALEC holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 1,972,875
Date: 10 Nov 2025
Ownership: See footnote
Footnotes: F2

ALEC holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 652,500
Date: 10 Nov 2025
Ownership: See footnote
Footnotes: F3

ALEC holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 652,500
Date: 10 Nov 2025
Ownership: See footnote
Footnotes: F4

ALEC holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 652,500
Date: 10 Nov 2025
Ownership: See footnote
Footnotes: F5

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

ALEC transaction Derivative

Employee Stock Option (right to buy)

Award

Transaction value: $0
Shares: +522,500
Change %
Price: $0.000000
Shares after: 522,500
Date: 10 Nov 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 522,500
Exercise price: $1.31
Footnotes: F6

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 6 footnotes

Footnote F1

The reported shares are represented by restricted stock units, or RSUs, which vest in 12 equal quarterly installments beginning on December 1, 2025.

Footnote F2

The reported securities are held directly by The Rosenthal Family Revocable Trust Dated November 4, 1994, as restated on June 9, 1999, for which the Reporting Person serves as trustee.

Footnote F3

The reported securities are held directly by the Adi Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

Footnote F4

The reported securities are held directly by the Noam Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

Footnote F5

The reported securities are held directly by the Shani Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

Footnote F6

Shares subject to the option vest in 48 equal monthly installments beginning on December 10, 2025.