X0306 4 2022-01-03 0 0001653087 Alector, Inc. ALEC 0001895592 Kenkare-Mitra Sara C/O ALECTOR, INC. 131 OYSTER POINT BLVD., SUITE 600 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 President and Head of R&D Common Stock 2022-01-03 4 A 0 59000 0.00 A 59000 D Common Stock 2022-01-03 4 A 0 59000 0.00 A 118000 D Employee Stock Option (right to buy) 20.78 2022-01-03 4 A 0 300000 0.00 A 2032-01-03 Common Stock 300000 300000 D Shares consist of restricted stock units, or RSUs, which vest as follows: one-third of the RSUs vest on March 1, 2023 and one-twelfth of the RSUs vest quarterly thereafter. Shares consist of performance share units, or PSUs, which vest as follows: twenty-five percent of the award will be earned if, within four years of January 3, 2022, the Issuer's average closing stock price is $30 per share for 40 consecutive trading days and the remaining seventy-five 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. Twenty-five percent of the shares subject to the option shall vest on December 15, 2022 and one forty-eighth of the shares vest monthly thereafter. /s/ David Oh, by power of attorney 2022-01-05