Alector, Inc. — Director's Dealing 2021

May 11, 2021

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Alector, Inc. (ALEC)
CIK: 0001653087
Period of Report: 2021-05-07

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2021-05-07	Common Stock	A	150000	$0.00	Acquired	1455226	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	2612500	Indirect
Common Stock	712500	Indirect
Common Stock	712500	Indirect
Common Stock	712500	Indirect

Footnotes

F1: The reported shares are represented by performance share units, or PSUs. Fifty percent of the award will be earned if the Issuer's average closing stock price is $30 per share for 40 consecutive trading days and an additional fifty percent will be earned if the average closing stock price is $40 per share for 40 consecutive trading days. Upon attainment of the performance metrics, the shares vest in four equal quarterly installments beginning on the first vesting date as set forth in the PSU award agreement.

F2: 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.

F3: The reported securities are held directly by the Adi Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

F4: The reported securities are held directly by the Noam Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

F5: The reported securities are held directly by the Shani Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.