144 0001757770 XXXXXXXX LIVE 0001653087 Alector, Inc. 001-38792 131 Oyster Point Blvd. Suite 600 South San Francisco CA 94080 (415)-231-5660 Arnon Rosenthal Officer Director Common Stock E*TRADE Financial Corporation

3 Edison Drive Alpharetta GA 30005

5233 29148 83830300 09/05/2023 Nasdaq Common Stock 09/01/2023 Vesting of Restricted Stock Units Issuer N 14931 09/01/2023 (1) N Arnon Rosenthal

C/O Alector, Inc. 131 Oyster Point Blvd., Suite 600 South San Francisco CA 94080

Common Stock 06/02/2023 5255 36279 (1) The securities to be sold were received upon the settlement of vested restricted stock units. 09/01/2023 /s/ Jordan Hochstrasser, by power of attorney