[Form 4] Alector, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Arnon Rosenthal, who serves as Chief Executive Officer and a director of Alector, Inc. (ALEC), reported a sale of 51,562 shares of common stock on 09/02/2025 at a weighted average price of $2.4968 per share to satisfy tax obligations arising from the vesting of restricted stock units (RSUs). After the reported sale, the filing shows 2,350,220 shares directly beneficially owned by the reporting person. Additional indirect holdings are disclosed across family trusts totaling 3,930,375 shares (1,972,875; 652,500; 652,500; 652,500). The filing also states that 150,000 performance share units (PSUs) were forfeited on May 6, 2025 because performance metrics were not achieved.

Positive

• Transparent disclosure of insider sale and the reason (tax obligations from RSU vesting)
• Significant retained ownership via direct and indirect holdings indicating ongoing insider alignment
• PSU structure enforces performance linkage, as evidenced by the forfeiture of 150,000 PSUs when metrics were not met

Negative

• Forfeiture of 150,000 PSUs reduces potential future equity compensation that could have vested
• Insider sale modestly reduces direct shareholdings (51,562 shares disposed)

Insights

Financial Analyst

TL;DR: Routine insider sale to cover taxes; ownership remains substantial and the PSU forfeiture slightly reduces potential future upside.

The reported disposition of 51,562 shares is described as tax-satisfaction following RSU vesting, which is a common, non-operational liquidity event and typically not material to a company’s operations or near-term valuation. The reporting person retains a sizeable combined direct and indirect stake (over 6 million shares disclosed across direct and trust holdings before and after the sale), indicating continued alignment with shareholder interests. The forfeiture of 150,000 PSUs reduces the pool of contingent shares that could have vested, modestly affecting future dilution assumptions.

Corporate Governance Expert

TL;DR: Disclosure is timely and detailed; sale appears procedural, while trust holdings indicate continued insider influence.

The Form 4 provides transparent disclosure of an insider sale tied to RSU tax obligations and enumerates indirect holdings through multiple family trusts for which the reporting person is trustee. This level of disclosure supports good governance practice from a reporting standpoint. The forfeiture of PSUs due to unmet performance targets demonstrates that compensation remains performance-contingent, which may be viewed positively by governance stakeholders.

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

OMB Number:			3235-0287
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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)
09/02/2025

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	09/02/2025		S(1)		51,562	D	$2.4968(2)	2,350,220(3)	D
Common Stock								1,972,875	I	See footnote(4)
Common Stock								652,500	I	See footnote(5)
Common Stock								652,500	I	See footnote(6)
Common Stock								652,500	I	See footnote(7)

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

Explanation of Responses:

1. The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.30 to $2.59. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

3. The reported amount excludes 150,000 shares previously reported as performance share units, or PSUs. Because the performance metrics were not attained during the PSU measurement period, these PSUs were forfeited on May 6, 2025.

4. 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.

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

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

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

	/s/ Grace Wong-Sarad, by power of attorney	09/04/2025
	** 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.
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FAQ

Why did ALEC insider Arnon Rosenthal sell 51,562 shares?

The filing states the shares were sold to satisfy tax obligations arising from RSU vesting.

How many shares does Arnon Rosenthal beneficially own after the reported transaction?

The Form 4 reports 2,350,220 shares directly beneficially owned following the sale, plus indirect trust holdings totaling 3,930,375 shares.

Were any performance awards forfeited by ALEC’s reporting person?

Yes, 150,000 performance share units (PSUs) were forfeited on May 6, 2025 because performance metrics were not attained.

What relationship does the reporting person have to ALEC?

The reporting person is listed as both Chief Executive Officer and a director of Alector, Inc.

Do the indirect holdings belong to trusts?

Yes, the indirect holdings are held by family trusts for which the reporting person serves as trustee.