SCHEDULE 13G

Alector Inc

Common Stock, $0.0001 par value per share · CUSIP: 014442107

Event date: 2026-10-19

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• RA Capital Management, L.P.

  Shares: 7,500,000.00 · Class: 5.1%

• Peter Kolchinsky

  Shares: 7,500,000.00 · Class: 5.1%

• Rajeev Shah

  Shares: 7,500,000.00 · Class: 5.1%

• RA Capital Healthcare Fund, L.P.

  Shares: 7,500,000.00 · Class: 5.1%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.