SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION	3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION Unaudited Financial Information — The unaudited condensed consolidated financial statements of the Company have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP"), and pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC"). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates ("ASU") promulgated by the Financial Accounting Standards Board. In the opinion of the Company, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the financial position and results of operations for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. The accompanying unaudited condensed consolidated financial statements include the accounts of Rallybio Corporation and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These accompanying unaudited condensed consolidated financial statements and notes should be read in conjunction with Rallybio's Annual Report on Form 10-K for the year ended December 31, 2025 (our "Annual Report"). The Company's significant accounting policies are described in Note 2 of the Notes to the consolidated financial statements included in our Annual Report. There have been no new accounting policies, including the adoption of new accounting standards during the three months ended March 31, 2026, unless otherwise noted below, which could be expected to materially impact the Company's unaudited condensed consolidated financial statements. Significant Accounting Policies — Future Milestone and Royalty Assets As part of the JV Sale, the Company received consideration including an estimated $3.0 million in future contingent milestones and royalty payments, which are recognized as a contingent consideration asset on the condensed consolidated balance sheets. The fair value of this contingent consideration was determined using a model that incorporates significant unobservable inputs based on Company estimates, external data, and management’s judgment and forecasts. Key assumptions in the model include the discount rate, the timing of expected cash flows, the probability of achieving the milestone and royalty payments, and projected future net revenues. The Company periodically reviews the carrying value of the contingent consideration when impairment indicators arise and records an impairment loss if the carrying amount materially exceeds the reassessed fair value. Increases in the carrying value are recognized only when contingent gains are realized. Since the contingent payments are tied to Phase 1 clinical study milestones and future royalty payments, the Company believes the likelihood of timely payment by Recursion is uncertain. Recently Issued Accounting Pronouncements—In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses ("ASU 2024-03"). This ASU requires public entities to disclose additional transparency on certain costs and expenses. ASU 2024-03 is effective for annual periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company has chosen not to early adopt this standard and is currently evaluating the potential impact of adopting this standard on its financial statements.

Unaudited Financial Information — The unaudited condensed consolidated financial statements of the Company have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP"), and pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC"). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates ("ASU") promulgated by the Financial Accounting Standards Board.

In the opinion of the Company, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the financial position and results of operations for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.

The accompanying unaudited condensed consolidated financial statements include the accounts of Rallybio Corporation and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

These accompanying unaudited condensed consolidated financial statements and notes should be read in conjunction with Rallybio's Annual Report on Form 10-K for the year ended December 31, 2025 (our "Annual Report"). The Company's significant accounting policies are described in Note 2 of the Notes to the consolidated financial statements included in our Annual Report. There have been no new accounting policies, including the adoption of new accounting standards during the three months ended March 31, 2026, unless otherwise noted below, which could be expected to materially impact the Company's unaudited condensed consolidated financial statements.

As part of the JV Sale, the Company received consideration including an estimated $3.0 million in future contingent milestones and royalty payments, which are recognized as a contingent consideration asset on the condensed consolidated balance sheets. The fair value of this contingent consideration was determined using a model that incorporates significant unobservable inputs based on Company estimates, external data, and management’s judgment and forecasts. Key assumptions in the model include the discount rate, the timing of expected cash flows, the probability of achieving the milestone and royalty payments, and projected future net revenues.

The Company periodically reviews the carrying value of the contingent consideration when impairment indicators arise and records an impairment loss if the carrying amount materially exceeds the reassessed fair value. Increases in the carrying value are recognized only when contingent gains are realized. Since the contingent payments are tied to Phase 1 clinical study milestones and future royalty payments, the Company believes the likelihood of timely payment by Recursion is uncertain.

Recently Issued Accounting Pronouncements—In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses ("ASU 2024-03"). This ASU requires public entities to disclose additional transparency on certain costs and expenses. ASU 2024-03 is effective for annual periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company has chosen not to early adopt this standard and is currently evaluating the potential impact of adopting this standard on its financial statements.