X0202 SCHEDULE 13G/A 0001103804 XXXXXXXX LIVE 4 Common Stock, par value $0.0001 per share 03/31/2026 0001739410 Rallybio Corporation 75120L209 234 Church Street New Haven CT 06510 Rule 13d-1(c) VIKING GLOBAL INVESTORS LP b DE 0 528954 0 528954 528954 N 9.99 PN See Item 4 Viking Global Opportunities Parent GP LLC b DE 0 528954 0 528954 528954 N 9.99 OO See Item 4 Viking Global Opportunities GP LLC b DE 0 528954 0 528954 528954 N 9.99 OO See Item 4 Viking Global Opportunities Portfolio GP LLC b DE 0 528954 0 528954 528954 N 9.99 OO See Item 4 Viking Global Opportunities Illiquid Investments Sub-Master LP b E9 0 528954 0 528954 528954 N 9.99 PN See Item 4 HALVORSEN OLE ANDREAS b Q8 0 528954 0 528954 528954 N 9.99 IN See Item 4 Shabet Rose Sharon b X1 0 528954 0 528954 528954 N 9.99 IN See Item 4 Rallybio Corporation 234 Church Street, New Haven, Connecticut, 06510 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"), 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, Mr. Ott has been removed 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 and Opportunities Portfolio GP 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 This Statement on Schedule 13G relates to shares of Common Stock and pre-funded warrants to purchase shares of Common Stock with an exercise price of $0.0001 per share (the "Warrants") held directly by VGOP. VGOP directly owns 524,347 shares of Common Stock and Warrants with the right to purchase 416,673 shares of Common Stock. However, the terms of the Warrants provide that no holder of Warrants shall have the right to exercise any portion of the Warrants to the extent that, after giving effect to such issuance after exercise, such holder of Warrants (together with its affiliates, any "group" or any other persons whose beneficial ownership could be aggregated with the holders) would beneficially own more than 9.99% of the number of shares of Common Stock outstanding immediately following exercise (the "Blocker"). Any holder of Warrants, upon notice to the Issuer, may increase or decrease the Blocker, subject to a maximum of 19.99%, but any such increase or decrease will not be effective until the 61st day after such notice is delivered to the Issuer. Accordingly, the amount of shares of Common Stock reported as beneficially owned by the Reporting Persons set forth herein excludes shares of Common Stock that the Reporting Persons do not currently have the right to purchase upon exercise of the Warrants held directly by VGOP due to the Blocker. VGI: 528,954 VGI provides managerial services to VGOP. VGI has the authority to dispose of and vote the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. VGI does not directly own any shares of Common Stock or Warrants. 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 that VGOP directly owns or has the right to purchase upon exercise of the Warrants. VGI beneficially owns 528,954 shares of Common Stock consisting of 524,347 shares of Common Stock directly owned by VGOP and 4,607 shares of Common Stock beneficially owned by VGOP, which VGOP has the right to purchase upon exercise of the Warrants, subject to the Blocker. Opportunities Parent: 528,954 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 that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Opportunities Parent does not directly own any shares of Common Stock or Warrants. Based on Rule 13d-3 under the Act, Opportunities Parent may be deemed to beneficially own the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Opportunities GP: 528,954 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 that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Opportunities GP does not directly own any shares of Common Stock or Warrants. Based on Rule 13d-3 under the Act, Opportunities GP may be deemed to beneficially own the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Opportunities Portfolio GP: 528,954 Opportunities Portfolio GP serves as the general partner of VGOP and has the authority to dispose of and vote the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Opportunities Portfolio GP does not directly own any shares of Common Stock or Warrants. Based on Rule 13d-3 under the Act, Opportunities Portfolio GP may be deemed to beneficially own the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. VGOP: 528,954 VGOP has the authority to dispose of and vote the shares of Common Stock that it directly owns or has the right to purchase upon exercise of the Warrants directly owned by it, subject to the Blocker, 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. O. Andreas Halvorsen and Rose S. Shabet: 528,954 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 or Warrants. Based on Rule 13d-3 under the Act, each may be deemed to beneficially own the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Mr. Halvorsen and Ms. Shabet each beneficially own 528,954 shares of Common Stock consisting of 524,347 shares of Common Stock directly owned by VGOP and 4,607 shares of Common Stock beneficially owned by VGOP, which VGOP has the right to purchase upon exercise of the Warrants, subject to the Blocker. The percentages set forth herein are based on (i) 5,290,236 shares of Common Stock outstanding as of March 31, 2026, as reported by the Issuer in its quarterly report on Form 10-Q, filed with the U.S. Securities and Exchange Commission (the "Commission") on May 13, 2026, and (ii) 4,607 shares of Common Stock that the Reporting Persons currently have the right to purchase upon exercise of the Warrants, subject to the Blocker. VGI: 9.99% Opportunities Parent: 9.99% Opportunities GP: 9.99% Opportunities Portfolio GP: 9.99% VGOP: 9.99% O. Andreas Halvorsen and Rose S. Shabet: 9.99% VGI: 0 Opportunities Parent: 0 Opportunities GP: 0 Opportunities Portfolio GP: 0 VGOP: 0 O. Andreas Halvorsen and Rose S. Shabet: 0 VGI: 528,954 Opportunities Parent: 528,954 Opportunities GP: 528,954 Opportunities Portfolio GP: 528,954 VGOP: 528,954 O. Andreas Halvorsen and Rose S. Shabet: 528,954 VGI: 0 Opportunities Parent: 0 Opportunities GP: 0 Opportunities Portfolio GP: 0 VGOP: 0 O. Andreas Halvorsen and Rose S. Shabet: 0 VGI: 528,954 Opportunities Parent: 528,954 Opportunities GP: 528,954 Opportunities Portfolio GP: 528,954 VGOP: 528,954 O. Andreas Halvorsen and Rose S. Shabet: 528,954 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 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, 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, 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).