Aktis Oncology, Inc.

S-11 d875386ds1.htm S-1

As filed with the Securities and Exchange Commission on December 19, 2025.

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

**FORMS-1 **

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Aktis Oncology, Inc.

(Exact name of registrant as specified in its charter)

**17 Drydock Avenue, Suite 17-401 **

Boston, Massachusetts 02210

**(617)461-4023 **

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

Matthew Roden, PhD

President and Chief Executive Officer

Aktis Oncology, Inc.

**17 Drydock Avenue, Suite 17-401 **

Boston, Massachusetts 02210

**Telephone: (617)461-4023 **

(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 is declared 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, 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, 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, anon-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 prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities nor does it seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to completion, dated December 19, 2025

Preliminary prospectus

*** shares***

This is an initial public offering of shares of common stock by Aktis Oncology, Inc.

We are offering shares of our common stock. The initial public offering price is expected to be between $ and $ per share.

Prior to this offering, there has been no public market for our common stock. We have applied to list our common stock on the Nasdaq Global Market under the trading symbol “AKTS,” and this offering is contingent upon the listing of our common stock on the Nasdaq Global Market.

We are an “emerging growth company” and a “smaller reporting company” as defined under the U.S. federal securities laws and, as such, will be subject to reduced public company reporting requirements for this prospectus and future filings. See “Prospectus summary—Implications of being an emerging growth company and a smaller reporting company.”

Investing in our common stock involves a high degree of risk. See “Risk factors” beginning on page 18 to read about factors you should consider before buying 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.

Following the completion of this offering, we will have two classes of common stock: common stock and Class A common stock. We are offering voting common stock in this offering, and unless otherwise noted, all references in this prospectus to our “common stock” refers to our voting common stock. The common stock and Class A common stock will be economically equivalent to each other. The rights of the holders of our common stock and Class A common stock will be identical, except with respect to voting and conversion. Each share of common stock will be entitled to one vote and will not be convertible into any other class of our share capital. The shares of Class A common stock will not have associated voting rights, except as otherwise expressly provided in our amended and restated certificate of incorporation and as may be required by law. Each share of non-voting Class A common stock may be converted at any time into one share of common stock at the option of its holder, subject to the beneficial ownership limitations provided for in our amended and restated certificate of incorporation. See “Description of capital stock—Common stock” for more information on the rights of the holders of our common stock and Class A common stock. The non-voting Class A common stock will not be listed for trading on any securities exchange.

We have granted the underwriters an option for a period of 30 days from the date of this prospectus to purchase up to additional shares of common stock from us at the initial public offering price less the underwriting discount.

The underwriters expect to deliver the shares against payment in New York, New York on , 2026.

Prospectus dated , 2026