4D Molecular Therapeutics (FDMT) 424B5Prospectus supplement for primary offering

Calculated in accordance with Rule 457(r) under the Securities Act of 1933, as amended (the “Securities Act”). Payment of the registration fee at the time of filing of the registrant’s Registration Statement on Form S-3 (File No. 333-276872) on February 5, 2024 was deferred pursuant to Rules 456(b) and 457(r) under the Securities Act and is paid herewith.

Includes 1,525,423 shares of common stock that the underwriters have an option to purchase and 3,583,476 shares of common stock that are issuable upon the exercise of pre-funded warrants referenced below.

Represents the sum of the pre-funded warrant sales price of $29.4999 per warrant and the exercise price of $0.0001 per share issuable pursuant to the pre-funded warrants. Pursuant to Securities and Exchange Commission staff interpretation, the entire fee is allocated to the common stock underlying the pre-funded warrants.