Rallybio Corp

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2025

OR

Commission File Number 001-40693

(Exact name of Registrant as specified in its Charter)

Registrant’s telephone number, including area code: (203)859-3820

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yeso No x

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. Yeso No x

Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x Noo

Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes x Noo

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, 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 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. o

If securities are registered pursuant to Section 12(b) of the Act, indicate by checkmark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. o

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b)o

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YESo NOx

The aggregate market value of the registrant's voting common stock held by non-affiliates as of June 30, 2025 was approximately $10.6 million, based on the closing price of the registrant’s common stock as reported by Nasdaq on that date.

The number of shares of Registrant’s common stock outstanding as of March 6, 2026 was 5,289,675.

DOCUMENTS INCORPORATED BY REFERENCE

None.

Cautionary Note Regarding Forward-Looking Statements

This Annual Report on Form 10-K contains forward-looking statements that are based on management’s beliefs and assumptions and on information currently available to management. All statements other than statements of historical facts contained in this Annual Report on Form 10-K are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements include, but are not limited to, statements concerning:

•our proposed Merger (as defined below) with Candid Therapeutics, Inc, a Delaware corporation ("Candid") and any potential benefits of the merger;

•the initiation, timing, progress, results, and cost of our research and development programs, and our current and future preclinical and clinical studies, including statements regarding timing of initiation and completion of our clinical trials for RLYB116, and related preparatory work, and the period during which the results of the trials will become available;

•the success, cost and timing of the clinical development of our product candidates, including RLYB116;

•the potential of our product candidates to treat certain target diseases;

•our ability to initiate, recruit and enroll patients in and conduct our clinical trials at the pace that we project;

•our ability to compete with companies currently marketing or engaged in the development of treatments for diseases that our product candidates are designed to target, including immune platelet transfusion refractoriness and refractory antiphospholipid syndrome;

•our reliance on third parties to conduct our clinical trials;

•enhancements to the manufacturing process for RLYB116;

•our reliance on third parties to manufacture drug substance and drug product for use in our clinical trials;

•our ability to identify and advance through clinical development any additional product candidates;

•our ability to obtain and maintain regulatory designations allowing for priority review of our product candidates, and our ability to obtain and maintain regulatory approval of our product candidates, and any related restrictions, limitations or warnings in the label of any of our product candidates, if approved;

•the size and growth potential of the markets for RLYB116 and any of our current product candidates or other product candidates we may identify and pursue, and our ability to serve those markets;

•the commercialization of our current product candidates and any other product candidates we may identify and pursue, if approved, including our ability to successfully build commercial infrastructure or enter into collaborations with third parties to market our current product candidates and any other product candidates we may identify and pursue;

•our ability to retain and recruit key personnel;

•our ability to obtain and maintain adequate intellectual property rights;

•our expectations regarding government and third-party payor coverage and reimbursement;

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•our estimates of our expenses, ongoing losses, capital requirements and our needs for or ability to obtain additional financing;

•our expected uses of the net proceeds from any future offerings;

•the potential benefits of strategic collaboration agreements and arrangements, including our agreement with Johnson & Johnson, and the expected timing of updates related thereto, our ability to enter into strategic collaborations or arrangements, including potential business development opportunities and potential licensing partnerships, and our ability to attract collaborators with development, regulatory and commercialization expertise;

•our expectations regarding the time during which we will be an emerging growth company under the Jumpstart Our Business Startups Act of 2012;

•our financial performance;

•developments and projections relating to our competitors or our industry; and

•other risks and uncertainties, including those listed under the section titled “Risk Factors.”

The forward-looking statements in this Annual Report on Form 10-K are only predictions and are based largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the date of this Annual Report on Form 10-K and are subject to a number of known and unknown risks, uncertainties and assumptions, including those described under the sections in this Annual Report on Form 10-K entitled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and elsewhere in this Annual Report on Form 10-K. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as guarantees of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual future results, levels of activity, performance and events and circumstances could differ materially from those projected in the forward-looking statements. Moreover, we operate in an evolving environment. New risks and uncertainties may emerge from time to time, and it is not possible for management to predict all risks and uncertainties. Except as required by applicable law, we are not obligated to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

Trademarks

We use Rallybio as a trademark in the United States ("U.S.") and/or in other countries. This Annual Report on Form 10-K contains references to our trademark and to those belonging to other entities, including Affibody®. Solely for convenience, trademarks and trade names referred to in this Annual Report on Form 10-K, including logos, artwork and other visual displays, may appear without the® or TM symbols, but such references are not intended to indicate in any way that we will not assert, to the fullest extent under applicable law, our rights or the rights of the applicable licensor to these trademarks and trade names. We do not intend our use or display of other entities’ trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of us by, any other entity.

Risk Factor Summary

Our business is subject to a number of risks that are discussed more fully in the “Risk Factors” section of this Annual Report on Form 10-K. These risks include the following:

•Failure to complete, or delays in completing, the proposed Merger with Candid could materially and adversely affect our results of operations, business, financial results and/or stock price;

•The Merger may be completed even though a material adverse effect may result from the announcement of the Merger, industry-wide changes and/or other causes;

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•Our stockholders may not realize a benefit from the Merger commensurate with the ownership dilution they will experience in connection with the Merger;

•We have incurred significant losses since our inception and anticipate that, if we continue to progress the development of our product candidates, we will continue to incur losses in the foreseeable future. We have not commercialized any products and have never generated revenue from the commercialization of any product. We are not currently profitable, and we may never achieve or sustain profitability;

•If we continue to progress the development of our product candidates, we will require significant additional capital to fund our operations. If we continue to progress the development of our product candidates and fail to obtain necessary financing, we may not be able to complete the development or commercialization of RLYB116 or any other product candidate. Given our limited resources and access to capital, we may decide to prioritize development of certain product candidates, the choice of which may prove to be wrong and adversely affect our business;

•Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our intellectual property or product candidates;

•Our failure to meet the listing standards of the Nasdaq Stock Market LLC, ("Nasdaq"), could result in the delisting of our common stock. Delisting could adversely affect the liquidity of our common stock and the market price of our common stock could decrease, and our ability to obtain sufficient additional capital to fund our operations and to continue to operate as a going concern would be substantially impaired;

•We are heavily dependent on the success of RLYB116, which is in early-stage clinical development. If we continue to progress the development of our product candidates, and we are not able to develop, obtain marketing approval for, or successfully commercialize our product candidates, or if we experience significant delays in doing so, our business will be materially harmed;

•Preclinical studies and clinical trials are expensive, time consuming and difficult to design and implement, and involve uncertain outcomes. If we continue to progress the development of our product candidates, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development of these product candidates;

•Enrollment and retention of patients in rare disease clinical trials is an expensive and time-consuming process and could be made more difficult or rendered impossible by multiple factors outside our control;

•If we continue to progress the development of our product candidates, results of preclinical studies, clinical trials or analyses that we may announce or publish from time to time, may not be indicative of results obtained in later trials, and any interim results we may publish could be different than final results;

•If we continue to progress the development of our product candidates, any product candidates that we develop or the administration thereof, may cause serious adverse events or undesirable side effects, which may halt their clinical development, delay or prevent marketing approval, or, if approved, require them to be taken off the market, include safety warnings, or otherwise limit their sales;

•The marketing approval processes of the U.S. Food and Drug Administration (the "FDA"), the European Medicines Agency (the "EMA"), and comparable foreign regulatory authorities, including the Medicines and Healthcare products Regulatory Agency in the United Kingdom (the “MHRA”), are lengthy, time-consuming, and inherently unpredictable, and if we continue to progress the development of our product candidates and are ultimately unable to obtain marketing approval for RLYB116 or any of our other product candidates, our business will be substantially harmed;

•Our product candidates target rare diseases and conditions, and if we continue to progress the development of our product candidates, the market opportunities for RLYB116 or any of our other

iii product candidates, if approved, may be smaller than we anticipate. We must be able to successfully identify patients and capture a significant market share to achieve profitability and growth;

•We face significant competition from biotechnology and pharmaceutical companies, and if we continue to progress the development of our product candidates, our operating results will suffer if we fail to compete effectively;

•If we continue to progress the development of our product candidates, we may pursue business development transactions and collaborate with third parties for the development and commercialization of our product candidates. We may not succeed in identifying and acquiring businesses or assets, in-licensing intellectual property rights or establishing and maintaining collaborations, which may significantly limit our ability to successfully develop and commercialize our other product candidates, if at all, and these transactions could disrupt our business, cause dilution to our stockholders or reduce our financial resources; and

•If we are unable to obtain, maintain and enforce patent protection for our technology and product candidates, or if the scope of the patent protection obtained is not sufficiently broad, our competitors could develop and commercialize technology and products similar or identical to ours, and our ability to successfully develop and commercialize our technology and product candidates may be adversely affected which may also impact the value of any potential CVR.

The foregoing is only a summary of some of our risks. For a more detailed discussion of these and other risks you should consider before making an investment in our common stock, see “Risk Factors.”

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