UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

Amendment No. 1

(Mark One)

For the fiscal year ended: December 31, 2018

Or

For the transition period from                      to                     

Commission file number: 001-38130

Aileron Therapeutics, Inc.

(Exact Name of Registrant as Specified in Its Charter)

490 Arsenal Way, Suite 210

Watertown, MA 02472

(Address of Principal Executive Offices) (zip code)

Registrant’s telephone number, including area code: (617) 995-0900

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ☐    No  ☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    Yes  ☐    No  ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).    Yes  ☒    No  ☐

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§229.405) is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  ☒

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or emerging growth company. See 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 13(a) of the Exchange Act.  ☒

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☒

As of June 29, 2018, the last day of the Registrant’s most recently completed second fiscal quarter, the aggregate market value of the voting and non-voting common equity held by non-affiliates of the Registrant, based on the last reported sale price of the shares of common stock on The Nasdaq Global Market was $40,753,229.

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

As of March 26, 2019, the Registrant has 14,875,035 shares of Common Stock, $0.001 par value per share, outstanding.

Documents incorporated by reference:

Portions of the Registrant’s definitive proxy statement for its 2019 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K.

EXPLANATORY NOTE

Aileron Therapeutics, Inc. (the “Company”) is filing this Amendment No. 1 on Form 10-K/A (“Amendment”) to its Annual Report on Form 10-K for the fiscal year ended December 31, 2018, as originally filed with the Securities and Exchange Commission on March 29, 2019 (the “Original Filing”), solely to replace Exhibit 23.1 Consent of Independent Registered Public Accounting Firm included in the Original Filing with a corrected Exhibit 23.1. The Exhibit 23.1 included in the Original Filing inadvertently omitted the Registration Statement on Form S-8 (No. 333-224785) from the list of registration statements as to which consent was provided by PricewaterhouseCoopers LLP. The Exhibit 23.1 included in the Original Filing also identified the report date as March 28, 2019 whereas the appropriate date is March 29, 2019. A new Exhibit 23.1 with the appropriate corrections is filed as Exhibit 23.1 attached hereto.

This Amendment speaks as of the original filing date and does not reflect events occurring after the filing of the Form 10-K or modify or update disclosures that may be affected by subsequent events. No revisions are being made to the Company’s financial statements or any other disclosure contained in the Form 10-K. This Amendment is an exhibit-only filing. Except for Exhibit 23.1, this Amendment does not otherwise update any exhibits as originally filed or previously amended.

In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), new certifications by the Company’s principal executive officer and principal financial officer are filed herewith as exhibits to this Amendment pursuant to Rule 13a-14(a) or 15d-14(a) of the Exchange Act. As no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4, and 5 of the certifications have been omitted. The Company is not including certifications pursuant to Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. 1350) as no financial statements are being filed with this Amendment.

PART IV

(c)    Exhibits.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

EXHIBIT 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Nos. 333-219158 and 333-224785) of Aileron Therapeutics, Inc. of our report dated March 29, 2019 relating to the financial statements, which appears in this Form 10-K.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

May 8, 2019

EXHIBIT 31.3

CERTIFICATION

I, Manuel C. Alves Aivado, certify that:

Date: May 8, 2019

EXHIBIT 31.4

CERTIFICATION

I, Donald V. Dougherty, certify that:

Date: May 8, 2019