Helen Susan Kim reports preferred stakes and option in Aktis Oncology (AKTS)

Rhea-AI Filing Summary

Aktis Oncology director and 10% owner Helen Susan Kim reported her initial beneficial ownership in the company as of January 8, 2026. Most of the reported holdings are indirect interests in Series A and Series B Redeemable Convertible Preferred Stock held by Vida Ventures II, LLC and Vida Ventures II-A, LLC, where investment and voting decisions may be made through affiliated management entities and committees, and each participant only benefits to the extent of their pecuniary interest.

Each share of Series A and Series B preferred stock is convertible into common stock on a 3.8044-for-1 basis and is expected to convert automatically into common shares immediately before the closing of an initial public offering of Aktis Oncology common stock without additional payment. Kim also holds a stock option for 37,866 common shares at $18 per share, with 1/36 of the option vesting monthly starting January 8, 2026, subject to her continued service.

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Kim Helen Susan

(Last) (First) (Middle)

C/O AKTIS ONCOLOGY, INC.

17 DRYDOCK AVENUE, SUITE 17-401

(Street)

BOSTON MA 02210

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
01/08/2026

3. Issuer Name and Ticker or Trading Symbol
Aktis Oncology, Inc. [ AKTS ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Redeemable Convertible Preferred Stock	(1)	(1)	Common Stock	3,900,284	(1)	I	See Footnote(2)
Series A Redeemable Convertible Preferred Stock	(1)	(1)	Common Stock	108,229	(1)	I	See Footnote(3)
Series B Redeemable Convertible Preferred Stock	(4)	(4)	Common Stock	959,086	(4)	I	See Footnote(2)
Series B Redeemable Convertible Preferred Stock	(4)	(4)	Common Stock	26,613	(4)	I	See Footnote(3)
Stock Option (Right to Buy)	(5)	01/07/2036	Common Stock	37,866	$18	D

Explanation of Responses:

1. Each share of Series A Redeemable Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 3.8044-for-1 basis and has no expiration date. All shares of Series A Redeemable Convertible Preferred Stock will automatically convert on a 3.8044-for-1 basis into shares of Common Stock immediately prior to the closing of the Issuer's initial public offering of its Common Stock without payment of additional consideration.

2. These shares are held by Vida Ventures II, LLC ("VV II"). VV Manager II, LLC ("VVM II") is the manager of VV II and may be deemed to have voting, investment and dispositive power with respect to the shares held by VV II. Arie Belldegrun, Fred Cohen, and Leonard Potter, the members of the management committee of VVM II, along with the other members of the investment committee of VVM II, Rajul Jain, Joshua Kazam, and the Reporting Person, a member of the Issuer's board of directors, may be deemed to share voting, investment and dispositive power over the shares held by VV II and each such person disclaims beneficial ownership of the securities except to the extent of such person's pecuniary interest therein.

3. These shares are held by Vida Ventures II-A, LLC ("VV II-A"). VVM II is the manager of VV II-A and may be deemed to have voting, investment and dispositive power with respect to the shares held by VV II-A. Arie Belldegrun, Fred Cohen, and Leonard Potter, the members of the management committee of VVM II, along with the other members of the investment committee of VVM II, Rajul Jain, Joshua Kazam, and the Reporting Person, a member of the Issuer's board of directors, may be deemed to share voting, investment and dispositive power over the shares held by VV II-A and each such person disclaims beneficial ownership of the securities except to the extent of such person's pecuniary interest therein.

4. Each share of Series B Redeemable Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 3.8044-for-1 basis and has no expiration date. All shares of Series B Redeemable Convertible Preferred Stock will automatically convert on a 3.8044-for-1 basis into shares of Common Stock immediately prior to the closing of the Issuer's initial public offering of its Common Stock without payment of additional consideration.

5. 1/36th of the original number of shares subject to the option shall vest in monthly installments from January 8, 2026, subject to the Reporting Person's continuous service to the Issuer on and through each vesting date, inclusive.

Remarks:

Exhibit 24 - Power of Attorney

	/s/ Helen Susan Kim	01/08/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What does the Aktis Oncology (AKTS) Form 3 filed by Helen Susan Kim show?

The Form 3 shows that Helen Susan Kim, a director and 10% owner of Aktis Oncology, reported indirect interests in preferred stock held through Vida Ventures entities and a stock option for 37,866 common shares at $18 per share as of January 8, 2026.

How are the preferred shares in Aktis Oncology (AKTS) convertible into common stock?

Both Series A and Series B Redeemable Convertible Preferred Stock are convertible into Aktis Oncology common stock on a 3.8044-for-1 basis and have no expiration date. All such preferred shares will automatically convert into common stock on the same basis immediately before the closing of an initial public offering of common stock without additional consideration.

Who actually holds the preferred shares reported in the Aktis Oncology (AKTS) Form 3?

The preferred shares are held by Vida Ventures II, LLC and Vida Ventures II-A, LLC. Their manager, VV Manager II, LLC, and members of its management and investment committees, including Helen Susan Kim, may be deemed to share voting, investment, and dispositive power, while each person disclaims beneficial ownership beyond their pecuniary interest.

What stock option did Helen Susan Kim report for Aktis Oncology (AKTS)?

Helen Susan Kim reported a stock option to buy 37,866 shares of Aktis Oncology common stock at an exercise price of $18 per share, expiring on January 7, 2036. The option vests in monthly installments of 1/36 of the original share amount starting January 8, 2026, subject to her continuous service.

Is the Helen Susan Kim Aktis Oncology (AKTS) Form 3 a purchase or sale of shares?

No purchase or sale is described; the Form 3 reports existing beneficial ownership as of January 8, 2026, including indirect interests in preferred stock and a stock option grant.

Why is Helen Susan Kim considered a 10% owner of Aktis Oncology (AKTS)?

She is identified as a director and 10% owner, reflecting the size of the interests associated with her through the reported preferred stock holdings and option position, as disclosed in the Form 3.