X0202 SCHEDULE 13G/A 0001103804 XXXXXXXX LIVE 1 Common Stock, par value $0.0001 per share 03/31/2026 0001835597 PepGen Inc. 713317105 321 Harrison Avenue 8th Floor Boston MA 02118 Rule 13d-1(c) VIKING GLOBAL INVESTORS LP b DE 0 3482434 0 3482434 3482434 N 5.03 PN See Item 4 Viking Global Opportunities Parent GP LLC b DE 0 3482434 0 3482434 3482434 N 5.03 OO See Item 4 Viking Global Opportunities GP LLC b DE 0 3482434 0 3482434 3482434 N 5.03 OO See Item 4 Viking Global Opportunities Portfolio GP LLC b DE 0 3482434 0 3482434 3482434 N 5.03 OO See Item 4 Viking Global Opportunities Illiquid Investments Sub-Master LP b E9 0 3482434 0 3482434 3482434 N 5.03 PN See Item 4 KAVRA 16 LLC b DE 0 1030680 0 1030680 1030680 1.5 OO See Item 4 HALVORSEN OLE ANDREAS b Q8 0 3482434 0 3482434 3482434 5.03 IN See Item 4 Shabet Rose Sharon b X1 0 3482434 0 3482434 3482434 5.03 IN See Item 4 PepGen Inc. 321 Harrison Avenue, 8th Floor, Boston, Massachusetts, 02118 Viking Global Investors LP ("VGI"), Viking Global Opportunities Parent GP LLC ("Opportunities Parent"), Viking Global Opportunities GP LLC ("Opportunities GP"), Viking Global Opportunities Portfolio GP LLC ("Opportunities Portfolio GP"), Viking Global Opportunities Illiquid Investments Sub-Master LP ("VGOP"), KAVRA 16 LLC ("KAVRA 16"), O. Andreas Halvorsen and Rose S. Shabet (collectively, the "Reporting Persons") Effective March 31, 2026, David C. Ott ("Mr. Ott") retired from his roles as Advisory Director of VGI and Executive Committee Member of each of Viking Global Partners LLC (the general partner of VGI) and Opportunities Parent. Accordingly, this Amendment No. 1 is being filed to remove Mr. Ott as a Reporting Person from this Schedule 13G, as Mr. Ott is no longer a beneficial owner of any of the shares of Common Stock reported herein. The business address of each of the Reporting Persons is: 600 Washington Boulevard, Floor 11, Stamford, Connecticut 06901. VGI is a Delaware limited partnership; Opportunities Parent, Opportunities GP, Opportunities Portfolio GP and KAVRA 16 are Delaware limited liability companies; VGOP is a Cayman Islands exempted limited partnership; O. Andreas Halvorsen is a citizen of Norway; and Rose S. Shabet is a citizen of the United States. Y VGI: 3,482,434 VGI provides managerial services to VGOP and KAVRA 16. VGI has the authority to dispose of and vote the shares of Common Stock directly held by VGOP and KAVRA 16. Based on Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Act"), VGI may be deemed to beneficially own the shares of Common Stock directly held by VGOP and KAVRA 16. VGI does not directly own any shares of Common Stock. VGI beneficially owns 3,482,434 shares of Common Stock consisting of (i) 2,451,754 shares of Common Stock directly and beneficially owned by VGOP and (ii) 1,030,680 shares of Common Stock directly and beneficially owned by KAVRA 16. Opportunities Parent: 3,482,434 Opportunities Parent is the sole member of Opportunities GP, which has the authority to dispose of and vote the shares of Common Stock controlled by Opportunities Portfolio GP, which consists of the shares of Common Stock directly held by VGOP and KAVRA 16. Opportunities Parent does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, Opportunities Parent may be deemed to beneficially own the shares of Common Stock directly held by VGOP and KAVRA 16. Opportunities Parent beneficially owns 3,482,434 shares of Common Stock consisting of (i) 2,451,754 shares of Common Stock directly and beneficially owned by VGOP and (ii) 1,030,680 shares of Common Stock directly and beneficially owned by KAVRA 16. Opportunities GP: 3,482,434 Opportunities GP serves as the sole member of Opportunities Portfolio GP and has the authority to dispose of and vote the shares of Common Stock controlled by Opportunities Portfolio GP, which consists of the shares of Common Stock directly held by VGOP and KAVRA 16. Opportunities GP does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, Opportunities GP may be deemed to beneficially own the shares of Common Stock directly held by VGOP. Opportunities GP beneficially owns 3,482,434 shares of Common Stock consisting of (i) 2,451,754 shares of Common Stock directly and beneficially owned by VGOP and (ii) 1,030,680 shares of Common Stock directly and beneficially owned by KAVRA 16. Opportunities Portfolio GP: 3,482,434 Opportunities Portfolio GP serves as the general partner of VGOP, which is the sole member of KAVRA 16, and has the authority to dispose of and vote the shares of Common Stock directly owned by VGOP and KAVRA 16. Opportunities Portfolio GP does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, Opportunities Portfolio GP may be deemed to beneficially own the shares of Common Stock directly held by VGOP and KAVRA 16. Opportunities Portfolio GP beneficially owns 3,482,434 shares of Common Stock consisting of (i) 2,451,754 shares of Common Stock directly and beneficially owned by VGOP and (ii) 1,030,680 shares of Common Stock directly and beneficially owned by KAVRA 16. VGOP: 3,482,434 VGOP has the authority to dispose of and vote the shares of Common Stock directly owned by it, which power may be exercised by its general partner, Opportunities Portfolio GP, and by VGI, an affiliate of Opportunities Portfolio GP, which provides managerial services to VGOP. Viking Global Opportunities LP (a Delaware limited partnership) and Viking Global Opportunities III LP (a Cayman Islands exempted limited partnership), through its investment in Viking Global Opportunities Intermediate LP (a Cayman Islands exempted limited partnership), invest substantially all of their assets in Viking Global Opportunities Master LP (a Cayman Islands exempted limited partnership), which in turn invests through VGOP. KAVRA 16: 1,030,680 KAVRA 16 has the authority to dispose of and vote the shares of Common Stock directly owned by it, which power may be exercised by Opportunities Portfolio GP, and by VGI, an affiliate of Opportunities Portfolio GP, which provides managerial services to KAVRA 16. The membership interests of KAVRA 16 are held by VGOP. Opportunities Portfolio GP is the general partner of VGOP. O. Andreas Halvorsen and Rose S. Shabet: 3,482,434 Mr. Halvorsen and Ms. Shabet, as Executive Committee Members of Viking Global Partners LLC (general partner of VGI) and Opportunities Parent, have shared authority to dispose of and vote the shares of Common Stock beneficially owned by VGI and Opportunities Parent. Neither Mr. Halvorsen nor Ms. Shabet directly owns any shares of Common Stock. Based on Rule 13d-3 under the Act, each may be deemed to beneficially own the shares of Common Stock directly held by VGOP and KAVRA 16. Mr. Halvorsen and Ms. Shabet each beneficially own 3,482,434 shares of Common Stock consisting of (i) 2,451,754 shares of Common Stock directly and beneficially owned by VGOP and (ii) 1,030,680 shares of Common Stock directly and beneficially owned by KAVRA 16. The percentages set forth herein are based on 69,167,958 shares of Common Stock outstanding as of March 31, 2026, as reported in the Issuer's quarterly report on Form 10-Q, filed with the Securities and Exchange Commission (the "Commission") on May 12, 2026. VGI: 5.03% Opportunities Parent: 5.03% Opportunities GP: 5.03% Opportunities Portfolio GP: 5.03% VGOP: 5.03% KAVRA 16: 1.5% O. Andreas Halvorsen and Rose S. Shabet: 5.03% VGI: 0 Opportunities Parent: 0 Opportunities GP: 0 Opportunities Portfolio GP: 0 VGOP: 0 KAVRA 16: 0 O. Andreas Halvorsen and Rose S. Shabet: 0 VGI: 3,482,434 Opportunities Parent: 3,482,434 Opportunities GP: 3,482,434 Opportunities Portfolio GP: 3,482,434 VGOP: 3,482,434 KAVRA 16: 1,030,680 O. Andreas Halvorsen and Rose S. Shabet: 3,482,434 VGI: 0 Opportunities Parent: 0 Opportunities GP: 0 Opportunities Portfolio GP: 0 VGOP: 0 KAVRA 16: 0 O. Andreas Halvorsen and Rose S. Shabet: 0 VGI: 3,482,434 Opportunities Parent: 3,482,434 Opportunities GP: 3,482,434 Opportunities Portfolio GP: 3,482,434 VGOP: 3,482,434 KAVRA 16: 1,030,680 O. Andreas Halvorsen and Rose S. Shabet: 3,482,434 Y N The response to Item 4 is incorporated by reference herein. Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. EXHIBIT A - JOINT FILING AGREEMENT VIKING GLOBAL INVESTORS LP /s/ Scott M. Hendler 05/15/2026 Viking Global Opportunities Parent GP LLC /s/ Scott M. Hendler 05/15/2026 Viking Global Opportunities GP LLC /s/ Scott M. Hendler 05/15/2026 Viking Global Opportunities Portfolio GP LLC /s/ Scott M. Hendler 05/15/2026 Viking Global Opportunities Illiquid Investments Sub-Master LP /s/ Scott M. Hendler 05/15/2026 KAVRA 16 LLC /s/ Scott M. Hendler 05/15/2026 HALVORSEN OLE ANDREAS /s/ Scott M. Hendler 05/15/2026 Shabet Rose Sharon /s/ Scott M. Hendler 05/15/2026 (1) Scott M. Hendler is signing on behalf of O. Andreas Halvorsen, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP (for itself and as manager of KAVRA 16 LLC), and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, and VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Mr. Halvorsen on February 12, 2021 (SEC File No. 005-49737). (2) Scott M. Hendler is signing on behalf of Rose S. Shabet, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP (for itself and as manager of KAVRA 16 LLC), and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, and VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Ms. Shabet on February 12, 2021 (SEC File No. 005-49737).