Alector insider plans $191K stock sale for taxes

Arnon Rosenthal plans to sell 79,702 ALEC shares worth about $191,285 as part of a Rule 144 tax-liability sale on Nasdaq around Sept. 2, 2026.

Rhea-AI Filing Summary

Alector, Inc. (ALEC) is the issuer for a planned insider sale of common stock under Rule 144 by Arnon Rosenthal. The notice covers the proposed sale of 79,702 shares of common stock through Morgan Stanley Smith Barney LLC, with an aggregate market value of $191,284.80, and an approximate sale date of September 2, 2026 on Nasdaq.

The securities relate to 156,646 shares received upon settlement of vested restricted stock units on September 1, 2026, with sales intended to satisfy tax obligations from this vesting. In the prior three months, Rosenthal sold 87,216 shares for proceeds of $172,188.09.

Key Figures

Shares to be sold: 79,702 shares Aggregate market value of planned sale: $191,284.80 Shares outstanding: 111,692,011 shares +5 more

8 metrics

Shares to be sold 79,702 shares Number of Alector, Inc. common shares to be sold under Rule 144

Aggregate market value of planned sale $191,284.80 Value of 79,702 shares of Alector, Inc. common stock to be sold

Shares outstanding 111,692,011 shares Alector, Inc. common shares outstanding referenced in the notice

RSU settlement shares 156,646 shares Shares received on September 1, 2026 upon RSU vesting

Shares sold in past 3 months 87,216 shares Common stock sold on June 2, 2026 by Arnon Rosenthal

Proceeds from past 3 months sales $172,188.09 Total proceeds from 87,216 shares sold on June 2, 2026

Approximate sale date September 2, 2026 Planned date for Rule 144 sale of Alector, Inc. shares

Date of notice September 1, 2026 Date the Rule 144 notice was signed and filed

Key Terms

Rule 144, restricted stock units, aggregate market value, vesting of Restricted Stock Units

4 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

restricted stock units financial

"The securities to be sold were received upon the settlement of vested restricted stock units, or RSUs."

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.

aggregate market value financial

"79702 | 191284.80 | 111692011 | 09/02/2026"

Aggregate market value is the combined price you would pay to buy all outstanding shares of a company or all companies in a group at current market prices — essentially the sum of each stock’s market capitalization. It matters to investors because it shows the overall size and weight of an investment or sector (like the total cost to buy every piece of a puzzle), helps compare scale across companies or markets, and influences index composition and risk exposure.

vesting of Restricted Stock Units financial

"Vesting of Restricted Stock Units | Issuer | | | 156646 | 09/01/2026"

FAQ

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

What does the Rule 144 notice disclose for Alector, Inc. (ALEC)?

It discloses a planned Rule 144 sale by Arnon Rosenthal of 79,702 shares of Alector, Inc. common stock, with an aggregate market value of $191,284.80, to be sold through Morgan Stanley Smith Barney LLC, with an approximate sale date of September 2, 2026 on Nasdaq.

How many ALEC shares did Arnon Rosenthal acquire from RSU vesting?

Arnon Rosenthal received 156,646 shares of Alector, Inc. common stock on September 1, 2026 upon settlement of vested restricted stock units. Shares to be sold are intended to satisfy tax obligations related to this RSU vesting.

How many ALEC shares are covered by the planned Rule 144 sale?

The notice states that 79,702 shares of Alector, Inc. common stock are to be sold, with an aggregate market value of $191,284.80. The approximate date of sale is September 2, 2026, and the shares are listed on Nasdaq.

What recent ALEC share sales has Arnon Rosenthal reported?

Over the past three months, Arnon Rosenthal reported selling 87,216 shares of Alector, Inc. common stock on June 2, 2026, for total proceeds of $172,188.09, as reflected in the Rule 144 notice.

How many ALEC shares are outstanding according to this notice?

The notice reports that Alector, Inc. has 111,692,011 shares of common stock outstanding, used as a reference figure in the Rule 144 disclosure for the proposed insider sale.

Why are some of Arnon Rosenthal’s ALEC shares being sold?

The remarks state that the reported Alector, Inc. shares were received upon RSU settlement and that shares covered by the notice will be sold to satisfy tax obligations arising from the vesting of those restricted stock units.

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

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Available on EDGAR 09/01/2026 - 08:00 PM EDT Accepted by SEC EDGAR 09/01/2026 - 08:00 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001757770
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Alector, Inc.
SEC File Number	001-38792
Address of Issuer	131 Oyster Point Blvd. Suite 600 South San Francisco CALIFORNIA 94080
Phone	(415)-231-5660
Name of Person for Whose Account the Securities are To Be Sold	Arnon Rosenthal
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer
Relationship to Issuer	Director

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	79702	191284.80	111692011	09/02/2026	Nasdaq

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	09/01/2026	Vesting of Restricted Stock Units	Issuer			156646	09/01/2026	(1)

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Arnon Rosenthal C/O Alector, Inc. 131 Oyster Point Blvd., Suite 600 South San Francisco CA 94080	Common Stock	06/02/2026	87216	172188.09

144: Remarks and Signature

Remarks	(1) The securities to be sold were received upon the settlement of vested restricted stock units, or RSUs. The reported shares will be sold to satisfy the reporting person's tax obligations in connection with the vesting of RSUs.
Date of Notice	09/01/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Grace Wong-Sarad, by power of attorney
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)