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FAIR VALUE MEASUREMENTS
 6 Months Ended
Jun. 30, 2026
Fair Value Disclosures [Abstract]  
FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS
ASC Topic 820, “Fair Value Measurement,” establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below:
Level 1:Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;
Level 2:
Quoted prices in markets that are not active, quoted prices for similar assets or liabilities in active markets, quoted prices or inputs that are observable, either directly or indirectly, for substantially the full term of the asset or liability and model-based valuation techniques (e.g., the Black-Scholes model) for which all significant inputs are observable in active markets;
Level 3:Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (supported by little or no market activity).
The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of assets and liabilities and their placement within the fair value hierarchy. The following methods and assumptions are used to estimate the fair value of each class of financial instruments for which it is practicable to estimate. The fair value of the Company’s accounts receivable, accounts payable, and accrued liabilities approximates their respective carrying amounts because of the immediate or short-term maturity of these financial instruments.
Cash, Cash Equivalents and Restricted Cash
The fair value of the Company’s cash, cash equivalents and restricted cash is classified within Level 1 of the fair value hierarchy. The carrying amounts reported in the unaudited Condensed Consolidated Balance Sheets approximate the fair value of cash, cash equivalents and restricted cash due to the short-term nature of these assets.
Short-term Investments
The fair value of the Company’s short-term investments, which are classified as available-for-sale securities, is estimated based on quoted prices in active markets and is classified as a Level 1 measurement.
Derivative Instrument
The Company’s derivative instrument pertains to the redemption feature included in the portion of the 2030 Notes that were issued in December 2024. This instrument’s fair value is measured using a binomial lattice model, which utilizes observable inputs (e.g., the Company’s stock price) and unobservable inputs (e.g., the expected volatility and instrument specific discount rate) that cause the valuation measurements to be classified as Level 3. The significant unobservable inputs used in the determination of the fair value of instruments classified as Level 3 have an inherent measurement uncertainty that, if
changed, could result in higher or lower fair value measurements of the derivative instrument as of the reporting date. The following assumptions were used within the model:
Valuation Assumptions:
June 30, 2026December 31, 2025
Expected volatility
76.2 %79.6 %
Risk-free interest rate
4.2 %3.7 %
Discount rate
8.2 %7.7 %
Dividend yield
— %— %
Term to maturity
3.7 years4.2 years
Stock price
$56.01$50.52
Convertible Notes
The fair value of the Company’s Convertible Notes is estimated based on quoted prices in active markets and is classified as a Level 1 measurement.
Samarium Project Loan
The fair value of the Company’s Samarium Project Loan is based on inputs that are directly observable for substantially the full term of the liability and is classified as a Level 2 measurement. Model-based valuation techniques for which all significant inputs are observable in active markets were used to calculate the fair value of this liability.
Equipment Notes
The fair value of the Company’s equipment notes is based on inputs that are directly observable for substantially the full term of the liability and is classified as a Level 2 measurement. Model-based valuation techniques for which all significant inputs are observable in active markets were used to calculate the fair values for these liabilities.
The Company’s financial instrument assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The carrying amounts and estimated fair values by input level of the Company’s financial instruments were as follows:
June 30, 2026
(in thousands)Carrying AmountFair ValueLevel 1Level 2Level 3
Financial assets:
Cash and cash equivalents$429,075 $429,075 $429,075 $— $— 
Short-term investments$1,023,564 $1,023,564 $1,023,564 $— $— 
Restricted cash$541 $541 $541 $— $— 
Derivative instrument
$11,583 $11,583 $— $— $11,583 
Financial liabilities:
2030 Notes
$847,267 $2,314,641 $2,314,641 $— $— 
Samarium Project Loan
$87,316 $98,536 $— $98,536 $— 
Equipment notes$29,099 $29,972 $— $29,972 $— 
December 31, 2025
(in thousands)Carrying AmountFair ValueLevel 1Level 2Level 3
Financial assets:
Cash and cash equivalents$1,166,011 $1,166,011 $1,166,011 $— $— 
Short-term investments$664,275 $664,275 $664,275 $— $— 
Restricted cash$1,348 $1,348 $1,348 $— $— 
Derivative instrument$8,708 $8,708 $— $— $8,708 
Financial liabilities:
2026 Notes
$67,411 $82,449 $82,449 $— $— 
2030 Notes
$845,301 $2,172,782 $2,172,782 $— $— 
Samarium Project Loan$86,029 $98,081 $— $98,081 $— 
Equipment notes$24,270 $25,339 $— $25,339 $— 
The following table summarizes the changes in fair value of the Company’s Level 3 assets measured on a recurring basis:
For the three months ended June 30,For the six months ended June 30,
(in thousands)
2026202520262025
Beginning balance
$12,806 $6,997 $8,708 $— 
Included in earnings(1)
(1,223)(2,529)2,875 4,468 
Ending balance
$11,583 $4,468 $11,583 $4,468 
(1)The gains (losses) are included in “Other income, net” within the Company’s unaudited Condensed Consolidated Statements of Operations.