Key facts
- This page summarizes Arnon Rosenthal's Form 4 filing for Alector, Inc. (ALEC).
- 16 reported transactions and 15 derivative rows are listed below.
- Accepted by SEC: 15 Oct 2026, 16:05.
Arnon Rosenthal - 13 Oct 2026 Form 4 Insider Report for Alector, Inc. (ALEC)
- Reporting relationship
- Chief Executive Officer, Director
- Issuer ticker
- ALEC
- Reported as of
- 13 Oct 2026
- Net transaction value
- $0
- SEC form
- 4
- Accepted by SEC
- 15 Oct 2026, 16:05:10 UTC
- Prior SEC filing
- 04 Sep 2026
- Source filing
- View source filing
- Reporting owner signature
- /s/ Grace Wong-Sarad, by power of attorney
Source evidence
Original filing metadata and source links for verification.
4 source fields
Reporting owner
1 detail
Filing notes and source
Key filing fact
Arnon Rosenthal filed Form 4 for Alector, Inc. (ALEC) on 15 Oct 2026.
Change
- Previous filing in this sequence was filed on 04 Sep 2026.
- 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
View source filing
Ownership activity is grounded in SEC Form 4 disclosures.
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
- 15 Oct 2026
Reported non-derivative transactions
Shares, units, or other non-derivative securities reported in this filing.
ALEC
transaction
Common Stock
Award
- Transaction value
- Shares
- +217,500
- Change %
- +9.5%
- Price
- $0.000000*
- Shares after
- 2,512,100
- Date
- 14 Oct 2026
- Ownership
- Direct
- Footnotes
- F1
ALEC
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 922,875
- Date
- 13 Oct 2026
- Ownership
- See footnote
- Footnotes
- F2
ALEC
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,002,500
- Date
- 13 Oct 2026
- Ownership
- See footnote
- Footnotes
- F3
ALEC
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,002,500
- Date
- 13 Oct 2026
- Ownership
- See footnote
- Footnotes
- F4
ALEC
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,002,500
- Date
- 13 Oct 2026
- 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)
Disposed to Issuer
- Transaction value
- Shares
- -500,000
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 500,000
- Exercise price
- $8.16
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +500,000
- Change %
- Price
- Shares after
- 500,000
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 500,000
- Exercise price
- $1.87
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Disposed to Issuer
- Transaction value
- Shares
- -275,000
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 275,000
- Exercise price
- $10.14
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +275,000
- Change %
- Price
- Shares after
- 275,000
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 275,000
- Exercise price
- $1.87
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Disposed to Issuer
- Transaction value
- Shares
- -520,000
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 520,000
- Exercise price
- $17.15
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +520,000
- Change %
- Price
- Shares after
- 520,000
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 520,000
- Exercise price
- $1.87
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Disposed to Issuer
- Transaction value
- Shares
- -457,038
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 457,038
- Exercise price
- $10.24
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +457,038
- Change %
- Price
- Shares after
- 457,038
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 457,038
- Exercise price
- $1.87
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Disposed to Issuer
- Transaction value
- Shares
- -417,213
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 417,213
- Exercise price
- $23.70
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +417,213
- Change %
- Price
- Shares after
- 417,213
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 417,213
- Exercise price
- $1.87
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Disposed to Issuer
- Transaction value
- Shares
- -119,446
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 119,446
- Exercise price
- $9.46
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +119,446
- Change %
- Price
- Shares after
- 119,446
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 119,446
- Exercise price
- $1.87
- Footnotes
- F6, F7, F8
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Disposed to Issuer
- Transaction value
- Shares
- -132,500
- Change %
- -100%
- Price
- Shares after
- 0
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 132,500
- Exercise price
- $6.48
- Footnotes
- F7, F8, F9
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +132,500
- Change %
- Price
- Shares after
- 132,500
- Date
- 13 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 132,500
- Exercise price
- $1.87
- Footnotes
- F7, F8, F9
ALEC
transaction
Derivative
Employee Stock Option (right to buy)
Award
- Transaction value
- Shares
- +978,750
- Change %
- Price
- $0.000000*
- Shares after
- 978,750
- Date
- 14 Oct 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 978,750
- Exercise price
- $1.88
- Footnotes
- F10
* marks a reported price that did not pass the local price check.
Additional SEC filing notes
Filing notes and footnotes
Explanation of responses 10 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, 2026.
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
The shares subject to the option are fully vested and immediately exercisable.
Footnote F7
The transactions reported herein reflect a one-time stock option repricing (the "Option Repricing") effective on October 13, 2026 (the "Effective Date"). The Option Repricing applies to stock options with exercise prices greater than $1.87 per share held by all continuing employees of the Issuer as of the Effective Date.
Footnote F8
Pursuant to the Option Repricing, the exercise price of the repriced options, including the reported option, has been amended to reduce the exercise price to $1.87 per share, the closing price of the Issuer's common stock on the Effective Date. However, if an employee exercises a repriced Eligible Option before the end of a "Retention Period" that begins on the Effective Date of the Option Repricing and ends on the earliest to occur of the following: (i) one year following the Effective Date; (ii) a Change in Control, as defined in the Issuer's 2019 Equity Incentive Plan, as amended (the "2019 Plan"); and (iii) the optionholder's death or Disability (as defined in the 2019 Plan), then the employee will be required to pay a premium exercise price that is equal to the original exercise price per share of such option. There was no change to the vesting schedules, expiration dates or number of shares underlying the repriced options.
Footnote F9
Shares subject to the option vest in 48 equal monthly installments beginning on November 1, 2023.
Footnote F10
Shares subject to the option vest in 48 equal monthly installments beginning on November 13, 2026.