Alector CEO sells shares for RSU tax obligations

Alector, Inc. Chief Executive Officer Arnon Rosenthal reported an open-market sale of 81,864 shares of common stock on March 2, 2026 at a weighted average price of $2.1233 per share.

Rhea-AI Filing Summary

Alector, Inc. Chief Executive Officer Arnon Rosenthal reported an open-market sale of 81,864 shares of common stock on March 2, 2026 at a weighted average price of $2.1233 per share. According to the footnotes, the shares were sold to satisfy his tax obligations arising from the vesting of restricted stock units.

After this sale, Rosenthal directly owns 2,338,176 shares of Alector common stock. He also has indirect holdings through family trusts, including 1,972,875 shares held by The Rosenthal Family Revocable Trust and 652,500 shares each held by the Adi Rosenthal 2007 Trust, the Noam Rosenthal 2007 Trust, and the Shani Rosenthal 2007 Trust, for which he serves as trustee.

Insider Trade Summary

Net Seller: 81,864 shares

Net Sell 5 txns

Insider Rosenthal Arnon

Role Chief Executive Officer

Sold 81,864 shs ($174K)

Type	Security	Shares	Price	Value
Sale	Common Stock	81,864	$2.1233	$174K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 2,338,176 shares (Direct); Common Stock — 3,930,375 shares (Indirect, See footnote)

Footnotes (6)

1. F1. 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. F2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.04 to $2.37. 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. F3. 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.
4. F4. The reported securities are held directly by the Adi Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.
5. F5. The reported securities are held directly by the Noam Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.
6. F6. The reported securities are held directly by the Shani Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Alector (ALEC) CEO Arnon Rosenthal report?

Arnon Rosenthal reported selling 81,864 shares of Alector common stock. The sale occurred on March 2, 2026, and was executed as an open-market transaction at a weighted average price of $2.1233 per share to cover tax obligations from RSU vesting.

Why did the Alector (ALEC) CEO sell 81,864 shares?

The CEO sold 81,864 shares to satisfy his tax obligations related to vesting restricted stock units. This type of sale is commonly used to cover withholding taxes when equity awards vest, rather than indicating a discretionary reduction in overall economic exposure.

At what price did Alector (ALEC) shares sell in the CEO’s Form 4 transaction?

The reported weighted average sale price was $2.1233 per share. The footnotes explain the shares were sold in multiple trades within a price range of $2.04 to $2.37, with full trade-by-trade details available upon request from appropriate parties.

How many Alector (ALEC) shares does the CEO own after the reported sale?

After the sale, the CEO directly owns 2,338,176 Alector common shares. In addition, Form 4 data show indirect ownership via family trusts, including 1,972,875 shares in a revocable family trust and 652,500 shares in each of three separate 2007 family trusts.

What indirect holdings in Alector (ALEC) does the CEO report through family trusts?

The filing reports 1,972,875 shares held by The Rosenthal Family Revocable Trust. It also lists 652,500 shares each in the Adi Rosenthal 2007 Trust, Noam Rosenthal 2007 Trust, and Shani Rosenthal 2007 Trust, with Arnon Rosenthal serving as trustee for these trusts.

Was the Alector (ALEC) CEO’s share sale a routine tax-related transaction?

Yes. A footnote explains the sale was executed to satisfy the CEO’s tax obligations from vesting restricted stock units. Such tax-related sales are often pre-planned mechanics linked to equity compensation rather than independent investment decisions to exit a stock position.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/03/2026 - 04:05 PM Learn about SEC filing dates

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
Estimated average burden
hours per response:			0.5

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)
03/02/2026

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	03/02/2026		S(1)		81,864	D	$2.1233(2)	2,338,176	D
Common Stock								1,972,875	I	See footnote(3)
Common Stock								652,500	I	See footnote(4)
Common Stock								652,500	I	See footnote(5)
Common Stock								652,500	I	See footnote(6)

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 $2.04 to $2.37. 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 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.

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

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

6. 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	03/03/2026
	** 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.
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