MPM BIOVENTURES 2018, L.P. - 12 Jan 2026 Form 4 Insider Report for Aktis Oncology, Inc. (AKTS)

Role
10%+ Owner
Signature
/s/ Luke Evnin
Issuer symbol
AKTS
Transactions as of
12 Jan 2026
Net transactions value
+$20,029,986
Form type
4
Filing time
14 Jan 2026, 18:19:26 UTC
Previous filing
08 Jan 2026

Reporting Owners (8)

Name Relationship Address Signature Signature date CIK
MPM BIOVENTURES 2018, L.P. 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Luke Evnin 14 Jan 2026 0001729505
EVNIN LUKE 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC, the GP of MPM BioVentures 2018 (B), L 14 Jan 2026 0001134657
MPM BIOVENTURES 2018 (B), L.P. 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC 14 Jan 2026 0001729504
MPM BioVentures 2018 LLC 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC 14 Jan 2026 0001818702
MPM BioVentures 2018 GP LLC 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC, the GP of MPM BioVentures 2018, L.P. 14 Jan 2026 0001818701
MPM ASSET MANAGEMENT INVESTORS BV2018 LLC 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the manager of MPM Asset Management Investors BV2018 LLC 14 Jan 2026 0001734817
MPM ONCOLOGY INNOVATIONS FUND LP 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, manager of MPM Oncology Innovations Fund GP LLC 14 Jan 2026 0001719960
MPM Oncology Innovations Fund GP LLC 10%+ Owner C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100, BOSTON /s/ Ansbert Gadicke, manager of MPM Oncology Innovations Fund GP LLC, the general partner of MPM Oncology Innovations Fund, L.P. 14 Jan 2026 0001857903

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction AKTS Common Stock Conversion of derivative security +1,314,262 +385% 1,655,971 12 Jan 2026 See Footnote F1, F2, F3, F4
transaction AKTS Common Stock Conversion of derivative security +5,914,197 +357% 7,570,168 12 Jan 2026 See Footnote F2, F3, F5, F6
transaction AKTS Common Stock Conversion of derivative security +1,577,119 +21% 9,147,287 12 Jan 2026 See Footnote F2, F3, F7, F8
transaction AKTS Common Stock Purchase $20,029,986 +1,112,777 +12% $18.00 10,260,064 12 Jan 2026 See Footnote F3, F9, F10

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction AKTS Series Seed Redeemable Convertible Preferred Stock Conversion of derivative security $0 -5,000,000 -100% $0.000000 0 12 Jan 2026 Common Stock 1,314,262 See Footnote F1, F2, F3
transaction AKTS Series A Redeemable Convertible Preferred Stock Conversion of derivative security $0 -22,500,000 -100% $0.000000 0 12 Jan 2026 Common Stock 5,914,197 See Footnote F2, F3, F5
transaction AKTS Series B Redeemable Convertible Preferred Stock Conversion of derivative security $0 -6,000,000 -100% $0.000000 0 12 Jan 2026 Common Stock 1,577,119 See Footnote F2, F3, F7
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 The shares of common stock were issued upon conversion as follows: 556,810 by MPM BioVentures 2018, L.P. ("BV 2018"), 29,593 by MPM BioVentures 2018 (B), L.P. ("BV 2018(B)"), 10,988 by MPM Asset Management Investors BV2018 LLC ("AM BV2018"), 119,478 by MPM Oncology Innovations Fund, L.P. ("MPM Oncology") and 597,393 by Oncology Impact Private Investment Fund 2, L.P. ("MPM Oncology Impact"). MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("BV2018 LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). BV 2018 LLC is the manager of AM BV2018. Drs. Evnin and Gadicke are managing directors of BV 2018 LLC and managers of MPM Oncology Innovations Fund GP LLC, which is the general partner of MPM Oncology. Dr. Gadicke is the managing member of MPM Oncology Investments 2 LLC, which is the general partner of MPM Oncology Impact.
F2 Each share of Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock automatically converted into shares of the Issuer's Common Stock on a 3.8044-for-1 basis into the number of shares of Common Stock shown in Column 7 without payment of further consideration upon the closing of the initial public offering of the Issuer's Common Stock. The Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock had no expiration date.
F3 The Reporting Persons disclaim beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.
F4 The shares are held as follows: 341,709 by MPM Asset Management LLC ("MPM AM"), 556,810 by BV 2018, 29,593 by BV 2018(B), 10,988 by AM BV2018, 119,478 by MPM Oncology and 597,393 by MPM Oncology Impact. Dr. Gadicke is the manager of MPM AM.
F5 The shares of common stock were issued upon conversion as follows: 2,505,648 by BV 2018, 133,170 by BV 2018(B), 49,452 by AM BV2018, 537,654 by MPM Oncology and 2,688,273 by MPM Oncology Impact.
F6 The shares are held as follows: 341,709 by MPM AM, 3,062,458 by BV 2018, 162,763 by BV 2018(B), 60,440 by AM BV2018, 657,132 by MPM Oncology and 3,285,666 by MPM Oncology Impact.
F7 The shares of common stock were issued upon conversion as follows: 668,173 by BV 2018, 35,512 by BV 2018(B), 13,187 by AM BV2018, 143,374 by MPM Oncology and 716,873 by MPM Oncology Impact.
F8 The shares are held as follows: 341,709 by MPM AM, 3,730,631 by BV 2018, 198,275 by BV 2018(B), 73,627 by AM BV2018, 800,506 by MPM Oncology and 4,002,539 by MPM Oncology Impact.
F9 The shares were purchased as follows: 219,897 by BV 2018, 8,689 by BV 2018(B), 4,284 by AM BV2018, 46,574 by MPM Oncology and 833,333 by MPM Oncology Impact.
F10 The shares are held as follows: 341,709 by MPM AM, 3,950,528 by BV 2018, 206,964 by BV 2018(B), 77,911 by AM BV2018, 847,080 by MPM Oncology and 4,835,872 by MPM Oncology Impact.

Remarks:

This filing is 1 of 2 identical filings due to limitations on number of Reporting Persons. See Form 4 filed by Ansbert Gadicke.