Alector CEO sells 72.6K shares for taxes

Alector’s CEO sold shares mainly to cover tax obligations from RSU vesting and remains a large direct and indirect shareholder.

Rhea-AI Filing Summary

Alector, Inc. (ALEC) disclosed that Chief Executive Officer and director Arnon Rosenthal sold 72,606 shares of common stock on September 3, 2026 at a weighted average price of $2.6647 per share, with trades occurring between $2.49 and $2.75. The sale was made to satisfy the reporting person’s tax obligations related to vesting restricted stock units. After this transaction, he directly holds 2,294,600 shares of Alector common stock and also reports additional indirect holdings as trustee of several family trusts.

Insider Trade Summary

Net Seller: 72,606 shares

Net Sell 5 txns

Insider Rosenthal Arnon

Role Chief Executive Officer

Sold 72,606 shs ($193K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	72,606	$2.6647	$193K
holding	Common Stock F3	--	--	--
holding	Common Stock F4	--	--	--
holding	Common Stock F5	--	--	--
holding	Common Stock F6	--	--	--

Holdings After Transaction: Common Stock — 2,294,600 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 $2.49 to $2.75. 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.

Key Figures

Shares sold: 72,606 shares Weighted average sale price: $2.6647 per share Sale price range: $2.49–$2.75 per share +1 more

4 metrics

Shares sold 72,606 shares Common stock sale reported for September 3, 2026

Weighted average sale price $2.6647 per share Average price for the 72,606 shares sold on September 3, 2026

Sale price range $2.49–$2.75 per share Range of individual transaction prices within the reported sale

Direct holdings after transaction 2,294,600 shares Direct Alector common stock held by Arnon Rosenthal following the sale

Key Terms

restricted stock units, weighted average price, indirect ownership, trustee

4 terms

restricted stock units financial

"tax obligations in connection with the vesting of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

indirect ownership financial

"The reported securities are held directly by the Rosenthal Family Revocable Trust"

trustee financial

"for which the Reporting Person serves as trustee."

A trustee is a person or institution legally appointed to hold and manage assets or enforce an agreement on behalf of other people (beneficiaries). Think of a trustee as a neutral referee or custodian who must act in the beneficiaries’ best interests, follow the trust or contract rules, and handle distributions, recordkeeping and enforcement. Investors care because a trustworthy trustee protects their rights, ensures promised payments or remedies are delivered, and can influence recoveries if things go wrong.

FAQ

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

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

Alector reported that CEO Arnon Rosenthal sold 72,606 shares of common stock on September 3, 2026. The sale is described as a disposition of common stock and is the only reported buy/sell transaction in this Form 4.

At what price were the Alector (ALEC) shares sold in this Form 4 filing?

The filing reports a weighted average price of $2.6647 per share, with the individual sale prices ranging from $2.49 to $2.75. Detailed breakdowns by exact price and share count are available from the company, the SEC staff, or security holders upon request.

Why did the Alector (ALEC) CEO sell 72,606 shares according to the Form 4?

The footnotes state that the 72,606 shares were sold to satisfy tax obligations incurred by the reporting person in connection with the vesting of restricted stock units (RSUs). The disclosure frames the sale as tax-related rather than a discretionary portfolio change.

How many Alector (ALEC) shares does the CEO hold directly after this reported sale?

After the September 3, 2026 sale, the Form 4 reports that Arnon Rosenthal directly holds 2,294,600 shares of Alector common stock. This figure reflects his direct ownership only and does not include additional indirect holdings through family trusts.

Does this Alector (ALEC) Form 4 indicate a Rule 10b5-1 trading plan for the CEO’s sale?

No. The document-level indicator for Rule 10b5-1 status is unchecked, and the footnotes do not describe the transaction as occurring under a Rule 10b5-1 or other pre-arranged trading plan.

What indirect Alector (ALEC) holdings are reported for the CEO in this Form 4?

The filing reports indirect ownership of common stock held by The Rosenthal Family Revocable Trust and three 2007 trusts for Adi, Noam, and Shani Rosenthal, for which Arnon Rosenthal serves as trustee. Specific share counts for these indirect positions are not listed in the data provided.

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

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Available on EDGAR 09/04/2026 - 05:45 PM Accepted by SEC EDGAR 09/04/2026 - 05:45 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 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)
09/03/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/03/2026		S(1)		72,606	D	$2.6647(2)	2,294,600	D
Common Stock								922,875	I	See footnote(3)
Common Stock								1,002,500	I	See footnote(4)
Common Stock								1,002,500	I	See footnote(5)
Common Stock								1,002,500	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 $2.49 to $2.75. 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	09/04/2026
	** 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)