SCHEDULE 13G/A

Lyell Immunopharma Inc

Common Stock par value $0.0001 per share · CUSIP: 55083R203

Event date: 2026-11-04

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

• ARCH Venture Fund IX, L.P.

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Fund IX Overage, L.P.

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Fund XIII, L.P.

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Partners IX, L.P.

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Partners IX Overage, L.P.

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Partners IX, LLC

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Partners XIII, L.P.

  Shares: 5,568,424 · Class: 17.4%

• ARCH Venture Partners XIII, LLC

  Shares: 5,568,424 · Class: 17.4%

• Keith Crandell

  Shares: 5,568,424 · Class: 17.4%

• Clinton Bybee

  Shares: 1,820,634 · Class: 5.7%

• Robert Nelsen

  Shares: 5,568,424 · Class: 17.4%

• Kristina Burow

  Shares: 5,568,424 · Class: 17.4%

• Steven Gillis

  Shares: 5,568,424 · Class: 17.4%

• Paul Berns

  Shares: 3,747,790 · Class: 11.7%

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