Officer Sale of Alector, Inc. Common Stock

Grace Wong-Sarad, Principal Accounting Officer of Alector, Inc., reported a sale of 1820 shares of common stock on April 16, 2026. The sale was executed at a price of $2.65 per share, totaling $4,823.00. Following this transaction, Wong-Sarad holds 104,645 shares of Alector, Inc. common stock. This transaction was conducted as part of a Rule 10b5-1 Trading Plan adopted on September 5, 2025, as indicated by footnote F1 and the aff10b5One field.