AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 13, 2026

REGISTRATION NO. 333-   

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

ENANTA PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

2019 Equity Incentive Plan

(As amended through March 11, 2026)

(Full title of the plan)

Jay R. Luly, Ph.D.

President and Chief Executive Officer

Enanta Pharmaceuticals, Inc.

4 Kingsbury Avenue

Watertown, Massachusetts 02472

(Name and address of agent for service)

(617) 607-0800

(Telephone number, including area code, of agent for service)

Copy to:

Stacie S. Aarestad

Ryan M. Rourke Reed

Foley Hoag LLP

155 Seaport Boulevard

Boston, Massachusetts 02110-2600

(617) 832-1000

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

EXPLANATORY NOTE

Enanta Pharmaceuticals, Inc. (the “Registrant”) is filing this Registration Statement on Form S-8 (this “Registration Statement”) to register an additional 1,600,000 shares of its common stock, par value $0.01 per share (the “Common Stock”), that may be issued and sold under the Enanta Pharmaceuticals, Inc. 2019 Equity Incentive Plan, as amended through March 11, 2026 (the “2019 Plan”), following the amendment to the 2019 Plan that was approved by the stockholders of the Registrant at its annual meeting on March 11, 2026. This Registration Statement is submitted in accordance with General Instruction E to Form S-8 regarding registration of additional securities, and pursuant to that instruction, the contents of the Registration Statements on Form S-8 (File Nos. 333-231384, 333-255957, 333-264794, 333-273800, 333-279217 and 333-287274) filed with the Securities and Exchange Commission on May 10, 2019, May  10, 2021, May 9, 2022, August  8, 2023, May 8, 2024 and May 14, 2025, are incorporated herein by reference.

Part II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 8. Exhibits.

1

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Watertown, Commonwealth of Massachusetts, on May 13, 2026.

POWER OF ATTORNEY

We, the undersigned officers and directors of Enanta Pharmaceuticals, Inc., hereby severally constitute and appoint each of Jay R. Luly, Ph.D. and Matthew P. Kowalsky, our true and lawful attorneys-in-fact, with full power to them in any and all capacities, to sign any and all amendments to this Registration Statement on Form S-8 (including any post-effective amendments thereto), and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact may do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

Exhibit 5.1

May 13, 2026

Enanta Pharmaceuticals, Inc.

4 Kingsbury Avenue

Watertown, MA 02472

To the Addressees:

We are familiar with the Registration Statement on Form S-8 (the “Registration Statement”) being filed by Enanta Pharmaceuticals, Inc., a Delaware corporation (the “Company”), with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), on the date hereof. The Registration Statement relates to the offer and sale by the Company of up to 1,600,000 shares (the “Shares”) of its common stock, par value $0.01 per share (“Common Stock”), issuable under the Company’s 2019 Equity Incentive Plan (as amended through March 11, 2026, the “2019 Plan”).

In arriving at the opinions expressed below, we have examined the Certificate of Incorporation and Bylaws of the Company, each as amended to date, the records of meetings and consents of the Company’s Board of Directors, or committees thereof, records of the proceedings of its stockholders deemed to be relevant to this opinion letter, and the 2019 Plan, each as provided to us by the Company, and the Registration Statement.

In addition, 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. In our examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to authentic original documents of all documents submitted to us as copies and the due authorization, execution and delivery of all documents by all persons other than the Company, where authorization, execution and delivery are prerequisites to the effectiveness of such documents. We have also made such investigations of law as we have deemed appropriate as a basis for the opinions expressed below.

We have assumed that the purchase price or other consideration to be received by the Company for the Shares will be valid consideration equal to or in excess of the par value thereof.

In rendering the opinion expressed below, we express no opinion other than as to the Delaware General Corporation Law.

On the basis of the foregoing, it is our opinion that the Shares, when issued and delivered in accordance with the terms of the 2019 Plan and the awards thereunder against the Company’s receipt of the purchase price or other consideration therefor, will be validly issued, fully paid and non-assessable.

This opinion is to be used only in connection with the offer and sale of the Shares while the Registration Statement is in effect.

Enanta Pharmaceuticals, Inc.

May 13, 2026

Page 2

This opinion is being delivered solely for the benefit of the Company and such other persons as are entitled to rely upon it pursuant to the applicable provisions of the Securities Act. This opinion may not be used, quoted, relied upon or referred to for any other purpose, nor may it be used, quoted, relied upon or referred to by any other person, for any purpose, without our prior written consent.

This opinion is based upon currently existing statutes, rules and regulations and judicial decisions and is rendered as of the date hereof, and we disclaim any obligation to advise you of any change in any of the foregoing sources of law or subsequent developments in law or changes in facts or circumstances which might affect any matters or opinions set forth herein.

We consent to the filing of this opinion as an exhibit to the Registration Statement. In giving such consent, we do not admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder.

This opinion letter shall be interpreted in accordance with the Core Opinion Principles jointly issued by the Committee on Legal Opinions of the American Bar Association’s Business Law Section and the Working Group on Legal Opinions Foundation as published in 74 Business Lawyer 815 (2019).

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of Enanta Pharmaceuticals, Inc. of our report dated November 19, 2025 relating to the financial statements, which appears in Enanta Pharmaceuticals, Inc.’s Annual Report on Form 10-K for the year ended September 30, 2025.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

May 13, 2026