Alector, Inc. — Director's Dealing 2021

Sep 23, 2021

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Alector, Inc. (ALEC)
CIK: 0001653087
Period of Report: 2021-09-22

Reporting Person: Rosenthal Arnon (Director, Chief Executive Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2021-09-22	Common Stock	S	94717	$25.289	Disposed	2317783	Indirect
2021-09-22	Common Stock	S	5283	$26.1007	Disposed	2312500	Indirect
2021-09-23	Common Stock	S	9625	$25.0979	Disposed	2302875	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1455226	Direct
Common Stock	712500	Indirect
Common Stock	712500	Indirect
Common Stock	712500	Indirect

Footnotes

F1: The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan.

F2: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $25.00 to $25.98, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and
Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in
footnotes (1), (3) and (4) to this Form 4.

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.

F4: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $26.00 to $26.22, inclusive.

F5: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $25.00 to $25.26, inclusive.