XML 16 R10.htm IDEA: XBRL DOCUMENT
v3.26.1

Financial Instruments | 6 Months Ended
--- | ---
Jun. 30, 2026
Financial Instruments Pledged as Collateral [Abstract] |
Financial Instruments | (3) Financial Instruments Investments The following table summarizes Cullinan’s investments by security type at June 30, 2026 (in thousands):
|  | Amortized Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized Losses |  |  | Estimated Fair Value |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |
U.S. government notes |  | $ | 129,965 |  |  | $ | 142 |  |  | $ | — |  |  | $ | 130,107 |
Corporate notes |  |  | 116,050 |  |  |  | 11 |  |  |  | (166 | ) |  |  | 115,895 |
Asset-backed securities |  |  | 9,887 |  |  |  | 9 |  |  |  | — |  |  |  | 9,896 |
Total short-term investments |  |  | 255,902 |  |  |  | 162 |  |  |  | (166 | ) |  |  | 255,898 |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |
Corporate notes |  |  | 19,150 |  |  |  | — |  |  |  | (130 | ) |  |  | 19,020 |
Total long-term investments |  |  | 19,150 |  |  |  | — |  |  |  | (130 | ) |  |  | 19,020 |
Total investments |  | $ | 275,052 |  |  | $ | 162 |  |  | $ | (296 | ) |  | $ | 274,918 |
The following table summarizes Cullinan’s investments by security type at December 31, 2025 (in thousands):
|  | Amortized Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized Losses |  |  | Estimated Fair Value |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |
U.S. government notes |  | $ | 159,632 |  |  | $ | 683 |  |  | $ | — |  |  | $ | 160,315 |
Corporate notes |  |  | 119,368 |  |  |  | 119 |  |  |  | (7 | ) |  |  | 119,480 |
Asset-backed securities |  |  | 9,717 |  |  |  | 52 |  |  |  | — |  |  |  | 9,769 |
Total short-term investments |  |  | 288,717 |  |  |  | 854 |  |  |  | (7 | ) |  |  | 289,564 |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |
Corporate notes |  |  | 48,134 |  |  |  | 90 |  |  |  | (2 | ) |  |  | 48,222 |
U.S. government notes |  |  | 9,963 |  |  |  | 85 |  |  |  | — |  |  |  | 10,048 |
Total long-term investments |  |  | 58,097 |  |  |  | 175 |  |  |  | (2 | ) |  |  | 58,270 |
Total investments |  | $ | 346,814 |  |  | $ | 1,029 |  |  | $ | (9 | ) |  | $ | 347,834 |
All of the Company's long-term investments as of June 30, 2026 and December 31, 2025 had maturities between one and two years from the respective balance sheet dates. The Company did not record any allowances for credit losses relating to its investments during the three and six months ended June 30, 2026 and 2025. Fair Value of Financial Instruments The following table sets forth the fair value of Cullinan’s financial assets that were measured at fair value on a recurring basis as of June 30, 2026 (in thousands):
|  | Level 1 |  |  | Level 2 |  |  | Level 3 |  |  | Total |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |
U.S. government notes |  | $ | — |  |  | $ | 130,107 |  |  | $ | — |  |  | $ | 130,107 |
Corporate notes |  |  | — |  |  |  | 115,895 |  |  |  | — |  |  |  | 115,895 |
Asset-backed securities |  |  | — |  |  |  | 9,896 |  |  |  | — |  |  |  | 9,896 |
Total short-term investments |  |  | — |  |  |  | 255,898 |  |  |  | — |  |  |  | 255,898 |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |
Corporate notes |  |  | — |  |  |  | 19,020 |  |  |  | — |  |  |  | 19,020 |
Total long-term investments |  |  | — |  |  |  | 19,020 |  |  |  | — |  |  |  | 19,020 |
Total investments |  | $ | — |  |  | $ | 274,918 |  |  | $ | — |  |  | $ | 274,918 |
The following table sets forth the fair value of the Company’s financial assets that were measured at fair value on a recurring basis as of December 31, 2025 (in thousands):
|  | Level 1 |  |  | Level 2 |  |  | Level 3 |  |  | Total |
Short-term investments |  |  |  |  |  |  |  |  |  |  |  |
U.S. government notes |  | $ | — |  |  | $ | 160,315 |  |  | $ | — |  |  | $ | 160,315 |
Corporate notes |  |  | — |  |  |  | 119,480 |  |  |  | — |  |  |  | 119,480 |
Asset-backed securities |  |  | — |  |  |  | 9,769 |  |  |  | — |  |  |  | 9,769 |
Total short-term investments |  |  | — |  |  |  | 289,564 |  |  |  | — |  |  |  | 289,564 |
Long-term investments |  |  |  |  |  |  |  |  |  |  |  |
Corporate notes |  |  | — |  |  |  | 48,222 |  |  |  | — |  |  |  | 48,222 |
U.S. government notes |  |  | — |  |  |  | 10,048 |  |  |  | — |  |  |  | 10,048 |
Total long-term investments |  |  | — |  |  |  | 58,270 |  |  |  | — |  |  |  | 58,270 |
Total investments |  | $ | — |  |  | $ | 347,834 |  |  | $ | — |  |  | $ | 347,834 |
As of June 30, 2026 and December 31, 2025, the fair values of Cullinan's cash and cash equivalents, prepaid expenses and other current assets, accounts payable, accrued expenses and other current liabilities approximated their carrying values due to the short-term nature of these instruments.

X
- Definition The entire disclosure for financial instruments. This disclosure includes, but is not limited to, fair value measurements of short and long term marketable securities, international currencies forward contracts, and auction rate securities. Financial instruments may include hedging and non-hedging currency exchange instruments, derivatives, securitizations and securities available for sale at fair value. Also included are investment results, realized and unrealized gains and losses as well as impairments and risk management disclosures. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org/825/tableOfContent + Details
Name: | us-gaap_FinancialInstrumentsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FinancialInstrumentsPledgedAsCollateralAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration