Document and Entity Information - USD ($)

12 Months Ended

Dec. 31, 2021

Mar. 28, 2022

Jun. 30, 2021

Cover [Abstract]

Document Type

10-K

Amendment Flag

false

Document Period End Date

Dec. 31, 2021

Document Fiscal Year Focus

2021

Document Fiscal Period Focus

FY

Document Annual Report

true

Document Transition Report

false

Entity Registrant Name

4D Molecular Therapeutics, Inc.

Entity Central Index Key

0001650648

Current Fiscal Year End Date

--12-31

Entity Well-known Seasoned Issuer

No

Entity Current Reporting Status

Yes

Entity Voluntary Filers

No

Entity Filer Category

Non-accelerated Filer

Entity Small Business

true

Entity Emerging Growth Company

true

Entity Ex Transition Period

false

ICFR Auditor Attestation Flag

false

Entity Shell Company

false

Entity Common Stock, Shares Outstanding

32,237,496

Entity Public Float

$ 444,521,977

Entity Interactive Data Current

Yes

Entity File Number

001-39782

Entity Tax Identification Number

47-3506994

Entity Address, Address Line One

5858 Horton Street #455

Entity Address, City or Town

Emeryville

Entity Address, State or Province

CA

Entity Address, Postal Zip Code

94608

City Area Code

(510)

Local Phone Number

505-2680

Entity Incorporation, State or Country Code

DE

Title of 12(b) Security

Common Stock, par value $0.0001 per share

Trading Symbol

FDMT

Security Exchange Name

NASDAQ

Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive Proxy Statement relating to the 2022 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. The proxy statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2021.

Auditor Firm ID

238

Auditor Name

PricewaterhouseCoopers LLP

Auditor Location

San Jose, California