Form 4 Filing for Mark Altmeyer

This filing details Form 4 transactions for Mark Altmeyer, a director at Alector, Inc. On June 17, 2026, Altmeyer acquired 28,700 shares of Common Stock, represented by restricted stock units that vest on June 17, 2027, or the next annual meeting. Additionally, an option to purchase 9,450 shares of Common Stock was granted, with vesting occurring in 12 monthly installments starting July 17, 2026, or earlier under specific conditions. Both transactions are reported as direct ownership.