EX-5.1

Exhibit 5.1


	140 Scott Drive Menlo Park, California 94025 Tel: +1.650.328.4600 Fax: +1.650.463.2600 www.lw.com
	FIRM / AFFILIATE OFFICES
	Beijing	Moscow
	Boston	Munich
	Brussels	New York
	Century City	Orange County
	Chicago	Paris
	Dubai	Riyadh
	Düsseldorf	San Diego
December 7, 2020	Frankfurt	San Francisco
	Hamburg	Seoul
	Hong Kong	Shanghai
	Houston	Silicon Valley
	London	Singapore
4D Molecular Therapeutics, Inc.	Los Angeles	Tokyo
5858 Horton Street #455	Madrid	Washington, D.C.
Emeryville, California 94608	Milan

Re:

Registration Statement on Form S-1 (File No. 333-250150)

Up to 5,476,189 Shares of Common Stock of 4D Molecular Therapeutics, Inc.

Ladies and Gentlemen:

We have acted as special counsel to 4D Molecular Therapeutics, Inc., a Delaware corporation (the “Company”), in connection with the proposed issuance of up to 5,476,189 shares of common stock, par value $0.0001 per share (the “Shares”). The Shares are included in a registration statement on Form S-1 under the Securities Act of 1933, as amended (the “Act”), filed with the Securities and Exchange Commission (the “Commission”) on December 4, 2020 (Registration No. 333-250150) (as amended, the “Registration Statement”). This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related prospectus (the “Prospectus”), other than as expressly stated herein with respect to the issue of the Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware (the “DGCL”), and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the purchasers and have been issued by the Company against payment therefor (not less than par value) in the circumstances contemplated by the form of underwriting agreement most recently filed as an exhibit to the Registration Statement, the issue and sale of the Shares will have been duly authorized by all necessary corporate action of the Company, and the Shares will be validly issued, fully paid and nonassessable. In rendering the foregoing opinion, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the DGCL.