SEC FORM 4

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

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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

CALIFORNIA

94080

(City)

(State)

(Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/13/2026

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	10/14/2026		A		217,500⁽¹⁾	A	$0	2,512,100	D
Common Stock								922,875	I	See footnote⁽²⁾
Common Stock								1,002,500	I	See footnote⁽³⁾
Common Stock								1,002,500	I	See footnote⁽⁴⁾
Common Stock								1,002,500	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Employee Stock Option (right to buy)	$8.16	10/13/2026		D			500,000	⁽⁶⁾	07/01/2028	Common Stock	500,000	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		500,000		⁽⁶⁾	07/01/2028	Common Stock	500,000	⁽⁷⁾⁽⁸⁾	500,000	D
Employee Stock Option (right to buy)	$10.14	10/13/2026		D			275,000	⁽⁶⁾	11/05/2028	Common Stock	275,000	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		275,000		⁽⁶⁾	11/05/2028	Common Stock	275,000	⁽⁷⁾⁽⁸⁾	275,000	D
Employee Stock Option (right to buy)	$17.15	10/13/2026		D			520,000	⁽⁶⁾	11/05/2029	Common Stock	520,000	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		520,000		⁽⁶⁾	11/05/2029	Common Stock	520,000	⁽⁷⁾⁽⁸⁾	520,000	D
Employee Stock Option (right to buy)	$10.24	10/13/2026		D			457,038	⁽⁶⁾	09/30/2030	Common Stock	457,038	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		457,038		⁽⁶⁾	09/30/2030	Common Stock	457,038	⁽⁷⁾⁽⁸⁾	457,038	D
Employee Stock Option (right to buy)	$23.7	10/13/2026		D			417,213	⁽⁶⁾	09/30/2031	Common Stock	417,213	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		417,213		⁽⁶⁾	09/30/2031	Common Stock	417,213	⁽⁷⁾⁽⁸⁾	417,213	D
Employee Stock Option (right to buy)	$9.46	10/13/2026		D			119,446	⁽⁶⁾	09/30/2032	Common Stock	119,446	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		119,446		⁽⁶⁾	09/30/2032	Common Stock	119,446	⁽⁷⁾⁽⁸⁾	119,446	D
Employee Stock Option (right to buy)	$6.48	10/13/2026		D			132,500	⁽⁹⁾	09/30/2033	Common Stock	132,500	⁽⁷⁾⁽⁸⁾	0	D
Employee Stock Option (right to buy)	$1.87	10/13/2026		A		132,500		⁽⁹⁾	09/30/2033	Common Stock	132,500	⁽⁷⁾⁽⁸⁾	132,500	D
Employee Stock Option (right to buy)	$1.88	10/14/2026		A		978,750		⁽¹⁰⁾	10/13/2036	Common Stock	978,750	$0	978,750	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, 2026.

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. The shares subject to the option are fully vested and immediately exercisable.

7. 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.

8. 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.

9. Shares subject to the option vest in 48 equal monthly installments beginning on November 1, 2023.

10. Shares subject to the option vest in 48 equal monthly installments beginning on November 13, 2026.

	/s/ Grace Wong-Sarad, by power of attorney	10/15/2026
	** 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.
* Form 4: SEC 1474 (03-26)