[Form 4] Alector, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Alector, Inc. (ALEC) reported insider equity awards to its Chief Executive Officer and Director. On 11/10/2025, the reporting person acquired 174,167 shares of Common Stock in the form of RSUs at $0. These RSUs vest in 12 equal quarterly installments beginning on December 1, 2025.

The reporting person was also granted an employee stock option to purchase 522,500 shares at an exercise price of $1.31 per share, vesting in 48 equal monthly installments beginning on December 10, 2025, and expiring on November 9, 2035. Following the reported transactions, the reporting person directly beneficially owned 2,524,387 shares. Additional shares are held indirectly through family trusts, as noted in the footnotes.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Rosenthal Arnon

(Last) (First) (Middle)

C/O ALECTOR, INC.

131 OYSTER POINT BLVD, SUITE 600

(Street)

SOUTH SAN FRANCISCO CA 94080

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Alector, Inc. [ ALEC ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/10/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/10/2025		A		174,167(1)	A	$0	2,524,387	D
Common Stock								1,972,875	I	See footnote(2)
Common Stock								652,500	I	See footnote(3)
Common Stock								652,500	I	See footnote(4)
Common Stock								652,500	I	See footnote(5)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (right to buy)	$1.31	11/10/2025		A		522,500		(6)	11/09/2035	Common Stock	522,500	$0	522,500	D

Explanation of Responses:

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

2. 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.

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

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

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

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

	/s/ Grace Wong-Sarad, by power of attorney	11/12/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did ALEC’s CEO acquire on 11/10/2025?

The reporting person acquired 174,167 Common Stock RSUs at $0.

How do the RSUs for ALEC’s CEO vest?

They vest in 12 equal quarterly installments beginning on December 1, 2025.

What are the terms of the stock option reported for ALEC?

An option to buy 522,500 shares at $1.31, vesting in 48 monthly installments starting December 10, 2025, expiring November 9, 2035.

How many shares does the reporting person directly own after the transactions?

Direct beneficial ownership was 2,524,387 shares following the reported transactions.

Are there indirect ALEC share holdings for the reporting person?

Yes. Additional shares are held indirectly through family trusts, as detailed in the footnotes.

What is the reporting person’s relationship to Alector (ALEC)?

The reporting person is a Director and Chief Executive Officer of Alector, Inc.