United States securities and exchange commission logo August 11, 2023 David Kirn, M.D. Chief Executive Officer 4D Molecular Therapeutics, Inc. 5858 Horton Street #455 Emeryville, CA 94608 Re: 4D Molecular Therapeutics, Inc. Registration Statement on Form S-3 Filed August 9, 2023 File No. 333-273845 Dear David Kirn: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding requests for acceleration. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or absence of action by the staff. Please contact Jason Drory at 202-551-8342 with any questions. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Phillip S. Stoup