3.26.1 html 152 371 1 false 61 0 false 7 false false R1.htm 0000001 - Document - Cover Sheet http://rallybio.com/role/Cover Cover Cover 1 false false R2.htm 0000002 - Document - Audit Information Sheet http://rallybio.com/role/AuditInformation Audit Information Cover 2 false false R3.htm 9952151 - Statement - Consolidated Balance Sheets Sheet http://rallybio.com/role/ConsolidatedBalanceSheets Consolidated Balance Sheets Statements 3 false false R4.htm 9952152 - Statement - Consolidated Balance Sheets (Parenthetical) Sheet http://rallybio.com/role/ConsolidatedBalanceSheetsParenthetical Consolidated Balance Sheets (Parenthetical) Statements 4 false false R5.htm 9952153 - Statement - Consolidated Statements of Operations and Comprehensive Loss Sheet http://rallybio.com/role/ConsolidatedStatementsofOperationsandComprehensiveLoss Consolidated Statements of Operations and Comprehensive Loss Statements 5 false false R6.htm 9952154 - Statement - Consolidated Statements of Changes in Stockholders' Equity Sheet http://rallybio.com/role/ConsolidatedStatementsofChangesinStockholdersEquity Consolidated Statements of Changes in Stockholders' Equity Statements 6 false false R7.htm 9952155 - Statement - Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) Sheet http://rallybio.com/role/ConsolidatedStatementsofChangesinStockholdersEquityParenthetical Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) Statements 7 false false R8.htm 9952156 - Statement - Consolidated Statements of Cash Flows Sheet http://rallybio.com/role/ConsolidatedStatementsofCashFlows Consolidated Statements of Cash Flows Statements 8 false false R9.htm 9952157 - Disclosure - BUSINESS Sheet http://rallybio.com/role/BUSINESS BUSINESS Notes 9 false false R10.htm 9952158 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION Sheet http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATION SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION Notes 10 false false R11.htm 9952159 - Disclosure - COLLABORATION AND LICENSE AGREEMENTS Sheet http://rallybio.com/role/COLLABORATIONANDLICENSEAGREEMENTS COLLABORATION AND LICENSE AGREEMENTS Notes 11 false false R12.htm 9952160 - Disclosure - MARKETABLE SECURITIES Sheet http://rallybio.com/role/MARKETABLESECURITIES MARKETABLE SECURITIES Notes 12 false false R13.htm 9952161 - Disclosure - LEASES Sheet http://rallybio.com/role/LEASES LEASES Notes 13 false false R14.htm 9952162 - Disclosure - BALANCE SHEET COMPONENTS Sheet http://rallybio.com/role/BALANCESHEETCOMPONENTS BALANCE SHEET COMPONENTS Notes 14 false false R15.htm 9952163 - Disclosure - STOCKHOLDERS' EQUITY Sheet http://rallybio.com/role/STOCKHOLDERSEQUITY STOCKHOLDERS' EQUITY Notes 15 false false R16.htm 9952164 - Disclosure - INCOME TAXES Sheet http://rallybio.com/role/INCOMETAXES INCOME TAXES Notes 16 false false R17.htm 9952165 - Disclosure - INVESTMENT IN JOINT VENTURE Sheet http://rallybio.com/role/INVESTMENTINJOINTVENTURE INVESTMENT IN JOINT VENTURE Notes 17 false false R18.htm 9952166 - Disclosure - COMMITMENTS AND CONTINGENCIES Sheet http://rallybio.com/role/COMMITMENTSANDCONTINGENCIES COMMITMENTS AND CONTINGENCIES Notes 18 false false R19.htm 9952167 - Disclosure - NET LOSS PER COMMON SHARE Sheet http://rallybio.com/role/NETLOSSPERCOMMONSHARE NET LOSS PER COMMON SHARE Notes 19 false false R20.htm 9952168 - Disclosure - SEGMENTS Sheet http://rallybio.com/role/SEGMENTS SEGMENTS Notes 20 false false R21.htm 9952169 - Disclosure - RESTRUCTURING Sheet http://rallybio.com/role/RESTRUCTURING RESTRUCTURING Notes 21 false false R22.htm 9952170 - Disclosure - SUBSEQUENT EVENTS Sheet http://rallybio.com/role/SUBSEQUENTEVENTS SUBSEQUENT EVENTS Notes 22 false false R23.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 23 false false R24.htm 995447 - Disclosure - Insider Trading Policies and Procedures Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc Insider Trading Policies and Procedures Notes 24 false false R25.htm 995550 - Disclosure - Cybersecurity Risk Management and Strategy Disclosure Sheet http://xbrl.sec.gov/cyd/role/CybersecurityRiskManagementAndStrategyDisclosure Cybersecurity Risk Management and Strategy Disclosure Notes 25 false false R26.htm 9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION (Policies) Sheet http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATIONPolicies SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION (Policies) Policies 26 false false R27.htm 9955512 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION (Tables) Sheet http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATIONTables SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION (Tables) Tables http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATION 27 false false R28.htm 9955513 - Disclosure - MARKETABLE SECURITIES (Tables) Sheet http://rallybio.com/role/MARKETABLESECURITIESTables MARKETABLE SECURITIES (Tables) Tables http://rallybio.com/role/MARKETABLESECURITIES 28 false false R29.htm 9955514 - Disclosure - LEASES (Tables) Sheet http://rallybio.com/role/LEASESTables LEASES (Tables) Tables http://rallybio.com/role/LEASES 29 false false R30.htm 9955515 - Disclosure - BALANCE SHEET COMPONENTS (Tables) Sheet http://rallybio.com/role/BALANCESHEETCOMPONENTSTables BALANCE SHEET COMPONENTS (Tables) Tables http://rallybio.com/role/BALANCESHEETCOMPONENTS 30 false false R31.htm 9955516 - Disclosure - STOCKHOLDERS' EQUITY (Tables) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYTables STOCKHOLDERS' EQUITY (Tables) Tables http://rallybio.com/role/STOCKHOLDERSEQUITY 31 false false R32.htm 9955517 - Disclosure - INCOME TAXES (Tables) Sheet http://rallybio.com/role/INCOMETAXESTables INCOME TAXES (Tables) Tables http://rallybio.com/role/INCOMETAXES 32 false false R33.htm 9955518 - Disclosure - NET LOSS PER COMMON SHARE (Tables) Sheet http://rallybio.com/role/NETLOSSPERCOMMONSHARETables NET LOSS PER COMMON SHARE (Tables) Tables http://rallybio.com/role/NETLOSSPERCOMMONSHARE 33 false false R34.htm 9955519 - Disclosure - SEGMENTS (Tables) Sheet http://rallybio.com/role/SEGMENTSTables SEGMENTS (Tables) Tables http://rallybio.com/role/SEGMENTS 34 false false R35.htm 9955520 - Disclosure - RESTRUCTURING (Tables) Sheet http://rallybio.com/role/RESTRUCTURINGTables RESTRUCTURING (Tables) Tables http://rallybio.com/role/RESTRUCTURING 35 false false R36.htm 9955521 - Disclosure - BUSINESS (Details) Sheet http://rallybio.com/role/BUSINESSDetails BUSINESS (Details) Details http://rallybio.com/role/BUSINESS 36 false false R37.htm 9955522 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION - Narrative (Details) Sheet http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATIONNarrativeDetails SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION - Narrative (Details) Details http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATIONTables 37 false false R38.htm 9955523 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION - Schedule of Property and Equipment Estimated Useful Lives (Details) Sheet http://rallybio.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESBASISOFPRESENTATIONANDPRINCIPLESOFCONSOLIDATIONScheduleofPropertyandEquipmentEstimatedUsefulLivesDetails SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION AND PRINCIPLES OF CONSOLIDATION - Schedule of Property and Equipment Estimated Useful Lives (Details) Details 38 false false R39.htm 9955524 - Disclosure - COLLABORATION AND LICENSE AGREEMENTS (Details) Sheet http://rallybio.com/role/COLLABORATIONANDLICENSEAGREEMENTSDetails COLLABORATION AND LICENSE AGREEMENTS (Details) Details http://rallybio.com/role/COLLABORATIONANDLICENSEAGREEMENTS 39 false false R40.htm 9955525 - Disclosure - MARKETABLE SECURITIES - Schedule of Fair Value of Marketable Securities by Type of Marketable Securities (Details) Sheet http://rallybio.com/role/MARKETABLESECURITIESScheduleofFairValueofMarketableSecuritiesbyTypeofMarketableSecuritiesDetails MARKETABLE SECURITIES - Schedule of Fair Value of Marketable Securities by Type of Marketable Securities (Details) Details 40 false false R41.htm 9955526 - Disclosure - MARKETABLE SECURITIES - Schedule of Marketable Securities by Balance Sheet Location Classification (Details) Sheet http://rallybio.com/role/MARKETABLESECURITIESScheduleofMarketableSecuritiesbyBalanceSheetLocationClassificationDetails MARKETABLE SECURITIES - Schedule of Marketable Securities by Balance Sheet Location Classification (Details) Details 41 false false R42.htm 9955527 - Disclosure - MARKETABLE SECURITIES - Schedule of Fair Values of Available-for-Sale Debt Securities by Contractual Maturity (Details) Sheet http://rallybio.com/role/MARKETABLESECURITIESScheduleofFairValuesofAvailableforSaleDebtSecuritiesbyContractualMaturityDetails MARKETABLE SECURITIES - Schedule of Fair Values of Available-for-Sale Debt Securities by Contractual Maturity (Details) Details 42 false false R43.htm 9955528 - Disclosure - MARKETABLE SECURITIES - Narrative (Details) Sheet http://rallybio.com/role/MARKETABLESECURITIESNarrativeDetails MARKETABLE SECURITIES - Narrative (Details) Details 43 false false R44.htm 9955529 - Disclosure - LEASES - Narrative (Details) Sheet http://rallybio.com/role/LEASESNarrativeDetails LEASES - Narrative (Details) Details 44 false false R45.htm 9955530 - Disclosure - LEASES -Schedule of Assets And Liabilities, Lessee (Details) Sheet http://rallybio.com/role/LEASESScheduleofAssetsAndLiabilitiesLesseeDetails LEASES -Schedule of Assets And Liabilities, Lessee (Details) Details 45 false false R46.htm 9955531 - Disclosure - LEASES - Schedule of Future Minimum Annual Lease Payments (Details) Sheet http://rallybio.com/role/LEASESScheduleofFutureMinimumAnnualLeasePaymentsDetails LEASES - Schedule of Future Minimum Annual Lease Payments (Details) Details 46 false false R47.htm 9955532 - Disclosure - BALANCE SHEET COMPONENTS - Schedule of Property and Equipment, Net (Details) Sheet http://rallybio.com/role/BALANCESHEETCOMPONENTSScheduleofPropertyandEquipmentNetDetails BALANCE SHEET COMPONENTS - Schedule of Property and Equipment, Net (Details) Details 47 false false R48.htm 9955533 - Disclosure - BALANCE SHEET COMPONENTS - Narrative (Details) Sheet http://rallybio.com/role/BALANCESHEETCOMPONENTSNarrativeDetails BALANCE SHEET COMPONENTS - Narrative (Details) Details 48 false false R49.htm 9955534 - Disclosure - BALANCE SHEET COMPONENTS - Schedule of Prepaid Expenses and Other Assets (Details) Sheet http://rallybio.com/role/BALANCESHEETCOMPONENTSScheduleofPrepaidExpensesandOtherAssetsDetails BALANCE SHEET COMPONENTS - Schedule of Prepaid Expenses and Other Assets (Details) Details 49 false false R50.htm 9955535 - Disclosure - BALANCE SHEET COMPONENTS - Schedule of Accrued Expenses (Details) Sheet http://rallybio.com/role/BALANCESHEETCOMPONENTSScheduleofAccruedExpensesDetails BALANCE SHEET COMPONENTS - Schedule of Accrued Expenses (Details) Details 50 false false R51.htm 9955536 - Disclosure - STOCKHOLDERS' EQUITY - Narrative (Details) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYNarrativeDetails STOCKHOLDERS' EQUITY - Narrative (Details) Details 51 false false R52.htm 9955537 - Disclosure - STOCKHOLDERS' EQUITY - Schedule of Share-based Compensation (Details) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYScheduleofSharebasedCompensationDetails STOCKHOLDERS' EQUITY - Schedule of Share-based Compensation (Details) Details 52 false false R53.htm 9955538 - Disclosure - STOCKHOLDERS' EQUITY - Schedule of Stock Option Activity (Details) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYScheduleofStockOptionActivityDetails STOCKHOLDERS' EQUITY - Schedule of Stock Option Activity (Details) Details 53 false false R54.htm 9955539 - Disclosure - STOCKHOLDERS' EQUITY - Schedule of Assumptions of Fair Value of Option Pricing Granted (Details) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYScheduleofAssumptionsofFairValueofOptionPricingGrantedDetails STOCKHOLDERS' EQUITY - Schedule of Assumptions of Fair Value of Option Pricing Granted (Details) Details 54 false false R55.htm 9955540 - Disclosure - STOCKHOLDERS' EQUITY - Schedule of Nonvested Restricted Common Stock Awards (Details) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYScheduleofNonvestedRestrictedCommonStockAwardsDetails STOCKHOLDERS' EQUITY - Schedule of Nonvested Restricted Common Stock Awards (Details) Details 55 false false R56.htm 9955541 - Disclosure - STOCKHOLDERS' EQUITY - Schedule of Nonvested Restricted Common Stock Units (Details) Sheet http://rallybio.com/role/STOCKHOLDERSEQUITYScheduleofNonvestedRestrictedCommonStockUnitsDetails STOCKHOLDERS' EQUITY - Schedule of Nonvested Restricted Common Stock Units (Details) Details 56 false false R57.htm 9955542 - Disclosure - INCOME TAXES - Narrative (Details) Sheet http://rallybio.com/role/INCOMETAXESNarrativeDetails INCOME TAXES - Narrative (Details) Details 57 false false R58.htm 9955543 - Disclosure - INCOME TAXES - Schedule of Income (Loss) Before Income Taxes (Details) Sheet http://rallybio.com/role/INCOMETAXESScheduleofIncomeLossBeforeIncomeTaxesDetails INCOME TAXES - Schedule of Income (Loss) Before Income Taxes (Details) Details 58 false false R59.htm 9955544 - Disclosure - INCOME TAXES - Schedule of Effective Income Tax Rates (Details) Sheet http://rallybio.com/role/INCOMETAXESScheduleofEffectiveIncomeTaxRatesDetails INCOME TAXES - Schedule of Effective Income Tax Rates (Details) Details 59 false false R60.htm 9955545 - Disclosure - INCOME TAXES - Schedule of Deferred Income Tax Benefits and Liabilities (Details) Sheet http://rallybio.com/role/INCOMETAXESScheduleofDeferredIncomeTaxBenefitsandLiabilitiesDetails INCOME TAXES - Schedule of Deferred Income Tax Benefits and Liabilities (Details) Details 60 false false R61.htm 9955546 - Disclosure - INVESTMENT IN JOINT VENTURE (Details) Sheet http://rallybio.com/role/INVESTMENTINJOINTVENTUREDetails INVESTMENT IN JOINT VENTURE (Details) Details http://rallybio.com/role/INVESTMENTINJOINTVENTURE 61 false false R62.htm 9955547 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details) Sheet http://rallybio.com/role/COMMITMENTSANDCONTINGENCIESDetails COMMITMENTS AND CONTINGENCIES (Details) Details http://rallybio.com/role/COMMITMENTSANDCONTINGENCIES 62 false false R63.htm 9955548 - Disclosure - NET LOSS PER COMMON SHARE - Schedule of Basic and diluted loss per common share (Details) Sheet http://rallybio.com/role/NETLOSSPERCOMMONSHAREScheduleofBasicanddilutedlosspercommonshareDetails NET LOSS PER COMMON SHARE - Schedule of Basic and diluted loss per common share (Details) Details 63 false false R64.htm 9955549 - Disclosure - NET LOSS PER COMMON SHARE - Narrative (Details) Sheet http://rallybio.com/role/NETLOSSPERCOMMONSHARENarrativeDetails NET LOSS PER COMMON SHARE - Narrative (Details) Details 64 false false R65.htm 9955550 - Disclosure - SEGMENTS (Details) Sheet http://rallybio.com/role/SEGMENTSDetails SEGMENTS (Details) Details http://rallybio.com/role/SEGMENTSTables 65 false false R66.htm 9955551 - Disclosure - RESTRUCTURING - Narrative (Details) Sheet http://rallybio.com/role/RESTRUCTURINGNarrativeDetails RESTRUCTURING - Narrative (Details) Details 66 false false R67.htm 9955552 - Disclosure - RESTRUCTURING - Schedule of Restructuring and Related Costs (Details) Sheet http://rallybio.com/role/RESTRUCTURINGScheduleofRestructuringandRelatedCostsDetails RESTRUCTURING - Schedule of Restructuring and Related Costs (Details) Details 67 false false R68.htm 9955553 - Disclosure - SUBSEQUENT EVENTS (Details) Sheet http://rallybio.com/role/SUBSEQUENTEVENTSDetails SUBSEQUENT EVENTS (Details) Details http://rallybio.com/role/SUBSEQUENTEVENTS 68 false false All Reports Book All Reports rlyb-20251231.htm rlyb-20251231.xsd rlyb-20251231_cal.xml rlyb-20251231_def.xml rlyb-20251231_lab.xml rlyb-20251231_pre.xml rlyb-20251231_g1.jpg rlyb-20251231_g2.jpg rlyb-20251231_g3.jpg rlyb-20251231_g4.jpg rlyb-20251231_g5.jpg rlyb-20251231_g6.jpg rlyb-20251231_g7.jpg http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/cyd/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/ecd/2025 true true