SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
Sep. 30, 2025
Accounting Policies [Abstract]
Principles of Consolidation	The accompanying unaudited condensed consolidated financial statements represent the historical operations of the standalone GRAIL legal entity and include purchase accounting adjustments and certain tax adjustments as if the Company filed a separate income tax return and was not included in Illumina’s consolidated return for the period of time the Company was owned by Illumina. All revenues and costs as well as assets and liabilities directly associated with the business activity of the Company are included in the unaudited condensed consolidated financial statements. Certain assets and liabilities were reflected at fair value under the new basis of accounting established at the closing of the Acquisition. Management considered the need to allocate any historical shared costs incurred by the parent, Illumina, to the accompanying unaudited condensed consolidated financial statements. As previously discussed, the European Commission adopted an order requiring Illumina and GRAIL to be held and operated as distinct and separate entities. As no integration ever occurred, management concluded that no material allocations were required. Prior to the Spin-Off, the Company had generated net operating loss carryforwards for federal and state tax purposes, however, as a single member LLC disregarded for tax purposes, these tax attributes are the sole property of Illumina and remained the assets of Illumina following the Spin-off in accordance with the Internal Revenue Code. However, amounts recognized by the Company are not necessarily representative of the amounts that would have been reflected in the financial statements had the Company operated independently of the parent. Related party transactions with Illumina are discussed further in Note 14 — Related Party Transactions.
Basis of Presentation	These unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. for interim financial information and pursuant to this Quarterly Report on Form 10-Q (“Form 10-Q”) and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. These unaudited condensed consolidated financial statements, reflect all normal recurring adjustments that are necessary to present the results fairly, and include the accounts of the Company and its wholly owned subsidiaries for the interim periods presented. All intercompany balances have been eliminated in consolidation. The results for the interim periods presented are not necessarily indicative of the results expected for any future period. The following information should be read in conjunction with the audited consolidated financial statements and notes thereto included in the 2024 Form 10-K.
Leases	Leases Leases are classified as operating or financing at lease inception and as necessary at modification. Leased assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. Operating leases are included in operating lease right-of-use (“ROU”) assets and operating lease liabilities in the consolidated balance sheets. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. When readily determinable, the Company uses the rate implicit in the lease to discount lease payments; however, when the rate is not readily determinable, the Company uses the incremental borrowing rate based on the information available at the commencement date. The incremental borrowing rate is the rate of interest that a company would have to pay to borrow an amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The operating lease ROU asset also includes any initial direct costs, lease payments made prior to lease commencement, and lease incentives received. Variable lease payments are expensed as incurred and are not included within the ROU asset and lease liability calculation. Variable lease payments primarily include reimbursements of costs incurred by lessors for common area maintenance and utilities. For each lease, the determined lease term is based on a noncancellable period, including any rent-free periods provided by the lessor, and may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease cost for lease payments is recognized on a straight-line basis over the lease term. Certain lease agreements contain lease and non-lease components. The Company accounts for non-lease components as part of the lease component to which they relate. The Company does not recognize ROU assets and lease liabilities for short-term leases, which have a lease term of twelve months or less and do not include an option to purchase the underlying asset that the Company is reasonably certain to exercise.
Intangible Assets	Intangible Assets Intangible assets identified in the Acquisition include GRAIL trade names, developed technology, and GRAIL in-process research and development (“IPR&D”) and were measured at fair value as of the Closing Date. The Company’s trade names, GRAIL and Galleri, have brand recognition in the market related to the services GRAIL provides customers and the research and development activities GRAIL performs. GRAIL’s developed technology includes intangible assets related to Galleri, its multi-cancer early detection test that was launched as a laboratory-developed test (“LDT”) in 2021, as well as a diagnostic aid for cancer (“DAC”) test. The developed technology underpins both Galleri, designed as a cancer screening test for asymptomatic individuals over 50 years of age, and DAC that is being designed to accelerate diagnostic resolution for patients for whom there is a clinical suspicion of cancer. The cost of identifiable intangible assets with finite lives, such as trade names and developed technology assets, are amortized on a straight-line basis over the assets’ respective estimated useful lives of 9 years and 18 years, respectively. The Company’s IPR&D includes assets related to GRAIL’s development of a minimal residual disease (“MRD”) test, a post-diagnostic test, that is currently under development. IPR&D is considered indefinite-lived and therefore is not amortized until completed and placed into service, at which point it will begin to be amortized over its estimated useful life or expensed upon abandonment of the associated research and development efforts. While IPR&D is not amortized, it is reviewed for impairment at least annually, or more frequently if events or circumstances indicate a potential for impairment. IPR&D is considered impaired if the carrying value of the reporting unit or IPR&D asset exceeds its respective fair value. During the indefinite-lived intangible asset impairment review, the Company assesses the qualitative factors to determine whether it is more likely than not that the fair value of the indefinite-lived intangible asset fair value is less than the carrying amount. The qualitative factors considered include, but are not limited to, macroeconomic conditions, industry and market considerations, and the Company’s overall financial performance. If the Company determines that it is not more likely than not that the intangible asset is less than the carrying amount, no additional assessment is necessary. If the carrying amount of the intangible asset exceeds its fair value, the Company records an impairment loss based on the excess. The Company may elect to bypass the qualitative assessment in a period and proceed to perform the quantitative indefinite-lived intangible asset impairment test.
Reclassification	Reclassification Certain amounts relating to related party transactions in the unaudited condensed consolidated statements of operations and statements of cash flows for the respective periods ended September 30, 2024 have been conformed to the current period presentation of related party transactions.
Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Not Yet Adopted In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This update improves income tax disclosure requirements, primarily through enhanced transparency and decision usefulness of disclosures. This guidance is effective for annual reporting periods beginning after December 15, 2024, with early adoption permitted, and can be applied on either a prospective or retroactive basis. The Company is currently compiling the information required for these disclosures and expects to provide the required disclosures in the year ending December 31, 2025. In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures. This update intends to improve financial reporting by requiring disclosure of additional information about specific expense categories. This guidance is effective for annual reporting periods beginning after December 15, 2026 and interim reporting periods beginning after December 15, 2027. Early adoption is permitted and the guidance is to be applied prospectively and may be applied retrospectively. The Company is currently evaluating the impact of this guidance on its consolidated financial statements and related disclosures. In July 2025, the FASB issued ASU No. 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. This update provides entities with a practical expedient related to developing reasonable and supportable forecasts as part of estimating expected credit losses, in which entities may elect to assume that current conditions as of the balance sheet date do not change for the remaining life of the asset. This guidance is effective for fiscal years beginning after December 15, 2025 and interim reporting periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the impact of this guidance on its consolidated financial statements and related disclosures. In September 2025, the FASB issued ASU No. 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. This update removes all references to software development project stages and requires entities to start capitalizing software costs when both of the following occur: (i) management has authorized and committed to funding the software project and (ii) it is probable that the project will be completed and the software will be used to perform the function intended. This guidance is effective for fiscal years beginning after December 15, 2027 and interim reporting periods within those annual reporting periods. Early adoption is permitted. The transition method may be prospective, modified, or retrospective. The Company is currently evaluating the impact of this guidance on its consolidated financial statements and related disclosures.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

9 Months Ended

Sep. 30, 2025

The accompanying unaudited condensed consolidated financial statements represent the historical operations of the standalone GRAIL legal entity and include purchase accounting adjustments and certain tax adjustments as if the Company filed a separate income tax return and was not included in Illumina’s consolidated return for the period of time the Company was owned by Illumina. All revenues and costs as well as assets and liabilities directly associated with the business activity of the Company are included in the unaudited condensed consolidated financial statements. Certain assets and liabilities were reflected at fair value under the new basis of accounting established at the closing of the Acquisition.

Management considered the need to allocate any historical shared costs incurred by the parent, Illumina, to the accompanying unaudited condensed consolidated financial statements. As previously discussed, the European Commission adopted an order requiring Illumina and GRAIL to be held and operated as distinct and separate entities. As no integration ever occurred, management concluded that no material allocations were required. Prior to the Spin-Off, the Company had generated net operating loss carryforwards for federal and state tax purposes, however, as a single member LLC disregarded for tax purposes, these tax attributes are the sole property of Illumina and remained the assets of Illumina following the Spin-off in accordance with the Internal Revenue Code. However, amounts recognized by the Company are not necessarily representative of the amounts that would have been reflected in the financial statements had the Company operated independently of the parent. Related party transactions with Illumina are discussed further in Note 14 — Related Party Transactions.

Basis of Presentation

These unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. for interim financial information and pursuant to this Quarterly Report on Form 10-Q (“Form 10-Q”) and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. These unaudited condensed consolidated financial statements, reflect all normal recurring adjustments that are necessary to present the results fairly, and include the accounts of the Company and its wholly owned subsidiaries for the interim periods presented. All intercompany balances have been eliminated in consolidation. The results for the interim periods presented are not necessarily indicative of the results expected for any future period. The following information should be read in conjunction with the audited consolidated financial statements and notes thereto included in the 2024 Form 10-K.

Leases

Leases are classified as operating or financing at lease inception and as necessary at modification. Leased assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease.

Operating leases are included in operating lease right-of-use (“ROU”) assets and operating lease liabilities in the consolidated balance sheets. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. When readily determinable, the Company uses the rate implicit in the lease to discount lease payments; however, when the rate is not readily determinable, the Company uses the incremental borrowing rate based on the information available at the commencement date. The incremental borrowing rate is the rate of interest that a company would have to pay to borrow an amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The operating lease ROU asset also includes any initial direct costs, lease payments made prior to lease commencement, and lease incentives received. Variable lease payments are expensed as incurred and are not included within the ROU asset and lease liability calculation. Variable lease payments primarily include reimbursements of costs incurred by lessors for common area maintenance and utilities.

For each lease, the determined lease term is based on a noncancellable period, including any rent-free periods provided by the lessor, and may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease cost for lease payments is recognized on a straight-line basis over the lease term. Certain lease agreements contain lease and non-lease components. The Company accounts for non-lease components as part of the lease component to which they relate.

The Company does not recognize ROU assets and lease liabilities for short-term leases, which have a lease term of twelve months or less and do not include an option to purchase the underlying asset that the Company is reasonably certain to exercise.

Intangible Assets

Intangible assets identified in the Acquisition include GRAIL trade names, developed technology, and GRAIL in-process research and development (“IPR&D”) and were measured at fair value as of the Closing Date.

The Company’s trade names, GRAIL and Galleri, have brand recognition in the market related to the services GRAIL provides customers and the research and development activities GRAIL performs. GRAIL’s developed technology includes intangible assets related to Galleri, its multi-cancer early detection test that was launched as a laboratory-developed test (“LDT”) in 2021, as well as a diagnostic aid for cancer (“DAC”) test. The developed technology underpins both Galleri, designed as a cancer screening test for asymptomatic individuals over 50 years of age, and DAC that is being designed to accelerate diagnostic resolution for patients for whom there is a clinical suspicion of cancer. The cost of identifiable intangible assets with finite lives, such as trade names and developed technology assets, are amortized on a straight-line basis over the assets’ respective estimated useful lives of 9 years and 18 years, respectively.

The Company’s IPR&D includes assets related to GRAIL’s development of a minimal residual disease (“MRD”) test, a post-diagnostic test, that is currently under development. IPR&D is considered indefinite-lived and therefore is not amortized until completed and placed into service, at which point it will begin to be amortized over its estimated useful life or expensed upon abandonment of the associated research and development efforts.

While IPR&D is not amortized, it is reviewed for impairment at least annually, or more frequently if events or circumstances indicate a potential for impairment. IPR&D is considered impaired if the carrying value of the reporting unit or IPR&D asset exceeds its respective fair value.

During the indefinite-lived intangible asset impairment review, the Company assesses the qualitative factors to determine whether it is more likely than not that the fair value of the indefinite-lived intangible asset fair value is less than the carrying amount. The qualitative factors considered include, but are not limited to, macroeconomic conditions, industry and market considerations, and the Company’s overall financial performance. If the Company determines that it is not more likely than not that the intangible asset is less than the carrying amount, no additional assessment is necessary. If the carrying amount of the intangible asset exceeds its fair value, the Company records an impairment loss based on the excess. The Company may elect to bypass the qualitative assessment in a period and proceed to perform the quantitative indefinite-lived intangible asset impairment test.

Reclassification

Certain amounts relating to related party transactions in the unaudited condensed consolidated statements of operations and statements of cash flows for the respective periods ended September 30, 2024 have been conformed to the current period presentation of related party transactions.

Accounting Pronouncements Not Yet Adopted

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This update improves income tax disclosure requirements, primarily through enhanced transparency and decision usefulness of disclosures. This guidance is effective for annual reporting periods beginning after December 15, 2024, with early adoption permitted, and can be applied on either a prospective or retroactive basis. The Company is currently compiling the information required for these disclosures and expects to provide the required disclosures in the year ending December 31, 2025.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures. This update intends to improve financial reporting by requiring disclosure of additional information about specific expense categories. This guidance is effective for annual reporting periods beginning after December 15, 2026 and interim reporting periods beginning after December 15, 2027. Early adoption is permitted and the guidance is to be applied prospectively and may be applied retrospectively. The Company is currently evaluating the impact of this guidance on its consolidated financial statements and related disclosures.

In July 2025, the FASB issued ASU No. 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. This update provides entities with a practical expedient related to developing reasonable and supportable forecasts as part of estimating expected credit losses, in which entities may elect to assume that current conditions as of the balance sheet date do not change for the remaining life of the asset. This guidance is effective for fiscal years beginning after December 15, 2025 and interim reporting periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the impact of this guidance on its consolidated financial statements and related disclosures.

In September 2025, the FASB issued ASU No. 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. This update removes all references to software development project stages and requires entities to start capitalizing software costs when both of the following occur: (i) management has authorized and committed to funding the software project and (ii) it is probable that the project will be completed and the software will be used to perform the function intended. This guidance is effective for fiscal years beginning after December 15, 2027 and interim reporting periods within those annual reporting periods. Early adoption is permitted. The transition method may be prospective, modified, or retrospective. The Company is currently evaluating the impact of this guidance on its consolidated financial statements and related disclosures.