Avalyn Pharma Inc.

S-11 ck0001540171-20260408.htm S-1

sAs filed with the Securities and Exchange Commission on April 8, 2026.

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

(Exact name of registrant as specified in its charter)

105 W First Street

Boston, Massachusetts 02127

(206) 707-0340

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Lyn Baranowski

Chief Executive Officer

105 W First Street

Boston, Massachusetts 02127

(206) 707-0340

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended, check the following box: ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

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. ☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state or other jurisdiction where the offer or sale is not permitted.

PRELIMINARY PROSPECTUS

Subject to Completion, Dated April 8, 2026

Shares

Common Stock

This is the initial public offering of shares of common stock of Avalyn Pharma Inc. We are offering shares of our common stock.

Prior to this offering, there has been no public market for our common stock. It is currently estimated that the initial public offering price per share will be between $ and $ . We have applied to list our common stock on the Nasdaq Global Market under the symbol “AVLN.” We believe that upon the completion of this offering, we will meet the standards for listing on the Nasdaq Global Market, and the completion of this offering is contingent upon such listing.

We are an “emerging growth company” and “smaller reporting company” as defined under the U.S. federal securities laws and, as such, we have elected to comply with certain reduced public company reporting requirements in this prospectus. For additional information, see “Prospectus Summary—Implications of Being an Emerging Growth Company and a Smaller Reporting Company.”

Investing in shares of our common stock involves a high degree of risk. See the section titled “Risk Factors” beginning on page 14 to read about factors you should consider before deciding to invest in shares of our common stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

(1)

For additional information regarding compensation payable to the underwriters, see the section titled “Underwriting.”

We have granted the underwriters the option to purchase up to an additional shares of common stock from us, at the initial public offering price, less the underwriting discounts and commissions.

The underwriters expect to deliver the shares against payment on or about , 2026.

Prospectus dated , 2026