v3.25.2
Debt
 6 Months Ended
Jun. 30, 2025
Debt Disclosure [Abstract]  
Debt Debt
Convertible Senior Notes Due 2029
On March 8, 2024, the Company completed an offering of $316.3 million aggregate principal amount of 1.50% Convertible Senior Notes due 2029 (the 2029 Notes). The proceeds from the issuance of the 2029 Notes were $306.8 million, net of debt issuance costs. The Company used approximately $246.1 million of the net proceeds to repurchase approximately $246.7 million in aggregate principal amount of its Convertible Senior Notes Due 2025 (the 2025 Notes) concurrently with the pricing of the 2029 Notes in privately negotiated transactions.
The Company also paid $1.3 million of accrued interest due at time of the note repurchase. As a result of the repurchase, the Company recognized a $1.3 million loss on extinguishment of debt in the condensed consolidated statement of operations for the six months ended June 30, 2024. The loss on extinguishment of debt included the unamortized debt issuance costs related to the portion of the 2025 Notes repurchased.
The Company used $30.0 million of the net proceeds to repurchase shares of the Company’s common stock from certain purchasers of the 2029 Notes at a purchase price equal to the last reported sale price per share of the Company’s common stock on March 5, 2024, which was $27.105 per share. In addition, the Company used $15.8 million of the net proceeds to pay the cost of the capped call transactions (2029 Capped Call Transactions) discussed below.
The 2029 Notes are the Company’s senior unsecured obligations. Interest is payable in cash semi-annually in arrears on March 15 and September 15 of each year beginning on September 15, 2024, at a rate of 1.50% per year. The 2029 Notes mature on March 15, 2029 unless repurchased, redeemed, or converted in accordance with their terms prior to the maturity date.
The initial conversion rate for the 2029 Notes is 28.9361 shares of common stock per $1,000 principal amount of the 2029 Notes, which is equivalent to an initial conversion price of approximately $34.56 per share of the Company’s common stock (2029 Notes Conversion Price). The conversion rate is subject to customary adjustments for certain events as described in the indenture governing the 2029 Notes.
The Company may not redeem the 2029 Notes before March 22, 2027. The Company has the option to redeem for cash all or any portion of the 2029 Notes on or after March 22, 2027 if the last reported sale price of the Company’s common stock has been at least 130% of the 2029 Notes Conversion Price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period, at a redemption price equal to 100% of the principal amount of the 2029 Notes to be redeemed, plus accrued and unpaid interest. No sinking fund is provided for the 2029 Notes.
Holders of the 2029 Notes may convert all or a portion of their 2029 Notes at their option before December 15, 2028, in multiples of $1,000 principal amounts, only under the following circumstances:
•during any calendar quarter commencing after the quarter ending on June 30, 2024 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock, for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the 2029 Notes Conversion Price on each applicable trading day;

•during the five business day period after any ten consecutive trading day period (the measurement period) in which the trading price per $1,000 principal amount of the 2029 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate of the 2029 Notes on such trading day;

•if the Company calls such 2029 Notes for redemption, at any time before the close of business on the scheduled trading day immediately preceding the redemption date, but only with respect to the 2029 Notes called (or deemed called) for redemption; or

•on the occurrence of specified corporate events.
On or after December 15, 2028, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their 2029 Notes, in integral multiples of $1,000 principal amount, at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock, at the Company’s election, in the manner and subject to the terms and conditions provided in the indenture governing the 2029 Notes.

Convertible Senior Notes Due 2025
In May 2020, the Company completed an offering of $287.5 million aggregate principal amount of 1.50% Convertible Senior Notes due 2025 (the 2025 Notes). The proceeds from the issuance of the Notes were $244.6 million, net of debt issuance costs and cash used to pay the cost of certain related capped call transactions. In March 2024, the Company repurchased for cash $246.7 million aggregate principal amount of the 2025 Notes, concurrently with the pricing of the 2029 Notes in privately negotiated transactions. The 2025 Notes matured in the second quarter of 2025, and the Company settled the balance of $40.8 million using existing cash balances.
The net carrying amount of the Company’s convertible senior notes on the condensed consolidated balance sheets consisted of the following (in thousands):
 June 30, 2025December 31, 2024
Principal amount:
Convertible Senior Notes Due 2025
$— $40,760 
Convertible Senior Notes Due 2029
316,250 316,250 
Total principal amount
316,250 357,010 
Unamortized debt issuance costs(7,104)(8,074)
Total debt, net
$309,146 $348,936 
Less: current portion
— (40,670)
Long-term senior convertible notes
$309,146 $308,266 
As of June 30, 2025, the if-converted value of the 2029 Notes did not exceed the principal amount. As of December 31, 2024, the if-converted value of the 2029 Notes exceeded the principal amount by $13.4 million.
The following table summarizes the effective interest rates for each of our convertible senior notes for the periods shown:
Three Months Ended June 30,Six Months Ended June 30,
 2025202420252024
Effective interest rate:
Convertible Senior Notes Due 2025(1)
2.2 %2.2 %2.2 %2.2 %
Convertible Senior Notes Due 2029
2.1 %2.1 %2.1 %2.1 %
(1) The effective interest rate presented represents the rate applicable for the period outstanding. The 2025 Notes matured in May 2025, and the outstanding principal balance was settled using cash balances.

The following table details interest expense related to the Notes recognized for the three and six months ended June 30, 2025 and 2024 (in thousands):
Three Months Ended June 30,Six Months Ended June 30,
2025202420252024
Contractual interest expense
$1,237 $1,339 $2,576 $2,484 
Amortization of debt issuance costs465 435 970 902 
Total interest expense$1,702 $1,774 $3,546 $3,386 
2029 Capped Call Transactions

In connection with the issuance of the 2029 Notes, the Company entered into Capped Call Transactions in March 2024 with certain counterparties at a net cost of $15.8 million (2029 Capped Call Transactions). The 2029 Capped Call Transactions are expected generally to reduce potential dilution to the Common Stock upon any conversion of the 2029 Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted 2029 Notes, as the case may be, with such reduction and/or offset subject to a cap based on a cap price initially equal to $42.0128 per share, and is subject to certain adjustments under the terms of the 2029 Capped Call Transactions.

2025 Capped Call Transactions

In connection with the issuance of the 2025 Notes, the Company entered into Capped Call Transactions in May 2020 with certain counterparties at a net cost of $34.1 million (2025 Capped Call Transactions). The 2025 Capped Call Transactions were expected generally to reduce potential dilution to the Common Stock upon any conversion of the 2025 Notes and/or offset any cash payments the Company was required to make in excess of the principal amount of converted 2025 Notes, as the case may be, with such reduction or offset subject to a cap. The cap price of the 2025 Capped Call Transactions was initially $173.18 per share of the Company’s common stock and was subject to certain adjustments under the terms of the 2025 Capped Call Transactions.

In connection with the repurchase of certain 2025 Notes, the Company entered into unwind agreements with the existing option counterparties in March 2024 to terminate a portion of the existing 2025 Capped Call Transactions in a notional amount corresponding to the amount of 2025 Notes repurchased (the Unwind Transactions). In connection with the Unwind Transactions, the Company received $0.2 million in cash as a termination payment with respect to the portion of the existing 2025 Capped Call Transactions that were unwound. The amount received was based generally on the termination values of the unwound portions of the existing 2025 Capped Call Transactions. The remaining 2025 Capped Call Transactions expired when the 2025 Notes matured in May 2025.
Promissory Note Payable

In connection with the acquisition of Capillary Biomedical, Inc. in 2022, the Company assumed a $4.7 million promissory note payable. The promissory note accrues interest at the rate of 5.0% per year, and becomes due and payable upon the first sale or license of the commercialized product. At June 30, 2025 and December 31, 2024, the loan balance, including accrued interest, was $4.9 million and $4.8 million, respectively, and was included as a component of other long-term liabilities on the condensed consolidated balance sheets.