In March 2021, the Company issued $375.0 million aggregate principal amount of 0% convertible senior notes due 2026, including $50.0 million aggregate principal amount of 2026 Notes issued upon the initial purchasers’ exercise in full of their option to purchase additional 2026 Notes. The 2026 Notes will mature on March 15, 2026, unless earlier redeemed or repurchased by the Company or converted by the holders pursuant to their terms. The Company will pay special interest, if any, at the Company’s election as the sole remedy relating to the failure to comply with certain reporting obligations and under certain circumstances.

The 2026 Notes are governed by an Indenture between the Company, as issuer, and U.S. Bank Trust Company National Association (as successor in interest to U.S. Bank National Association), as trustee (the “2026 Notes Indenture”). The 2026 Notes are unsecured and rank: senior in right of payment to the Company’s indebtedness that is expressly subordinated in right of payment to the 2026 Notes; equal in right of payment to the Company’s existing and future indebtedness that is not so subordinated, including its 0.125% convertible senior notes due 2024 (see 0.125% Convertible Senior Notes Due 2024 below); effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness; and structurally junior to all existing and future indebtedness and other liabilities incurred by the Company’s subsidiaries.

Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or a combination of cash and shares of common stock, at the Company’s election.

The 2026 Notes have an initial conversion rate of 5.5341 shares of common stock per $1,000 principal amount of 2026 Notes. This represents an initial effective conversion price of approximately $180.70 per share of common stock and initially approximately 2.1 million shares issuable upon conversion. Throughout the term of the 2026 Notes, the conversion rate may be adjusted upon the occurrence of certain events. Holders of the 2026 Notes will not receive any cash payment representing accrued and unpaid special interest, if any, upon conversion of a 2026 Note, except in limited circumstances. Accrued but unpaid special interest, if any, will be deemed to be paid by cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock paid or delivered, as the case may be, to the holder upon conversion of a 2026 Note.

Holders may convert all or a portion of their 2026 Notes prior to the close of business on the business day immediately preceding December 15, 2025, in multiples of $1,000 principal amount, only under the following circumstances:

On or after December 15, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their 2026 Notes at the conversion rate at any time regardless of whether the conditions set forth above have been met.

As of March 31, 2024, the 2026 Notes are not yet convertible at the option of the debt holder and were classified as long-term on the condensed consolidated balance sheets as of March 31, 2024 and December 31, 2023.

The 2026 Notes were not redeemable by the Company prior to March 20, 2024. The Company may redeem for cash all or any portion of the 2026 Notes, at its option, on or after March 20, 2024 if the last reported sale price of the Company’s common stock has been at least 130% of the 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 ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the 2026 Notes to be redeemed, plus accrued and unpaid special interest, if any, to, but excluding, the redemption date.

During the year ended December 31, 2023, the Company paid approximately $64.9 million in cash to repurchase approximately $74.7 million aggregate principal amount of the 2026 Notes and recognized an extinguishment gain in the amount of $8.8 million in gain on extinguishment of convertible notes, capped call modification and change in fair value on the consolidated statement of operations.

The 2026 Notes consist of the following (in thousands):


	As of			As of
	March 31, 2024			December 31, 2023
Liability component:
Principal	$	300,276		$	300,276
Less: debt discount, net of amortization		(3,287	)		(3,715	)
Net carrying amount	$	296,989		$	296,561

The following table sets forth total interest expense recognized related to the 2026 Notes (in thousands):


	Three Months Ended March 31,
	2024		2023
Amortization of debt discount and transaction costs	$	428	$	525

The effective interest rates on the 2026 Notes were 0.6% during both the three months ended March 31, 2024 and 2023.

The fair value of the 2026 Notes, which was determined based on inputs that are observable in the market or that could be derived from, or corroborated with, observable market data, quoted price of the 2026 Notes in an over-the-counter market (Level 2), and carrying value of debt instruments were as follows (in thousands):


	As of March 31, 2024				As of December 31, 2023
	Fair Value		Carrying Value		Fair Value		Carrying Value
2026 Notes	$	293,520	$	296,989	$	260,114	$	296,561

In connection with the issuance of the 2026 Notes, the Company entered into capped call transactions with certain option counterparties (the “2026 capped call transactions”). The 2026 capped call transactions are expected generally to reduce potential dilution to the Company’s common stock upon any conversion of the 2026 Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted 2026 Notes, as the case may be, with such reduction and/or offset subject to a cap. Under the 2026 capped call transactions, the Company purchased capped call options that in the aggregate relate to the total number of shares of the Company’s common stock underlying the 2026 Notes, with an initial strike price of approximately $180.70 per share, which corresponds to the initial conversion price of the 2026 Notes and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of the 2026 Notes, and with a cap price of approximately $258.14. The cost of the purchased capped calls of $35.1 million was recorded to shareholders’ equity and will not be re-measured.

Based on the closing price of the Company’s common stock of $34.83 on March 31, 2024, the if-converted value of the 2026 Notes was less than their respective principal amounts.

In December 2019, the Company issued $450.0 million aggregate principal amount of 0.125% convertible senior notes due 2024, including $75.0 million aggregate principal amount of 2024 Notes issued upon the initial purchasers’ exercise in full of their option to purchase additional 2024 Notes. The 2024 Notes will mature on December 15, 2024, unless earlier redeemed or repurchased by the Company or converted by the holders pursuant to their terms. Interest is payable semiannually in arrears on June 15 and December 15 of each year, commencing on June 15, 2020.

The 2024 Notes are governed by an Indenture between the Company, as issuer, and U.S. Bank Trust Company, National Association (as successor in interest to U.S. Bank National Association), as trustee (the “2024 Notes Indenture”). The 2024 Notes are unsecured and rank: senior in right of payment to the Company’s indebtedness that is expressly subordinated in right of payment to the 2024 Notes; equal in right of payment to the Company’s existing and future indebtedness that is not so subordinated, including its 2026 Notes; effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness; and structurally junior to all existing and future indebtedness and other liabilities incurred by the Company’s subsidiaries.

Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or a combination of cash and shares of common stock, at the Company’s election. The Company’s current intention is to settle the conversion in shares of common stock if a conversion were to occur.

The 2024 Notes have an initial conversion rate of 8.8999 shares of common stock per $1,000 principal amount of 2024 Notes. This represents an initial effective conversion price of approximately $112.36 per share of common stock and initially approximately 4.0 million shares issuable upon conversion. Throughout the term of the 2024 Notes, the conversion rate may be adjusted upon the occurrence of certain events. Holders of the 2024 Notes will not receive any cash payment representing accrued and unpaid interest, if any, upon conversion of a 2024 Note, except in limited circumstances. Accrued but unpaid interest will be deemed to be paid by cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock paid or delivered, as the case may be, to the holder upon conversion of a 2024 Note.

Holders may convert all or a portion of their 2024 Notes prior to the close of business on the business day immediately preceding June 15, 2024, in multiples of $1,000 principal amount, only under the following circumstances:

On or after June 15, 2024 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their 2024 Notes at the conversion rate at any time regardless of whether the conditions set forth above have been met.

As of March 31, 2024, the 2024 Notes were not convertible at the option of the debt holder and are classified as current liabilities on the condensed consolidated balance sheet as the 2024 Notes mature in less than 12 months.

The 2024 Notes were not redeemable by the Company prior to December 20, 2022. The Company may redeem for cash all or any portion of the 2024 Notes, at its option, on or after December 20, 2022 if the last reported sale price of the Company’s common stock has been at least 130% of the 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 ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the 2024 Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date.

During the year ended December 31, 2023, the Company paid approximately $65.7 million in cash to repurchase approximately $70.1 million aggregate principal amount of the 2024 Notes and recognized an extinguishment gain in the amount of $3.9 million in gain on extinguishment of convertible notes, capped call modification and change in fair value on the consolidated statement of operations. The Company also partially terminated capped call options entered into in connection with the 2024 Notes during the year ended December 31, 2023 and received approximately $33 thousand recorded to additional paid-in capital on the consolidated balance sheet.

During the year ended December 31, 2022, the Company paid approximately $288.8 million in cash to repurchase approximately $316.4 million aggregate principal amount of the 2024 Notes and recognized an extinguishment gain in the amount of $24.0 million in gain on extinguishment of convertible notes, capped call modification and change in fair value on the consolidated statement of operations.

The 2024 Notes consist of the following (in thousands):


	As of			As of
	March 31, 2024			December 31, 2023
Liability component:
Principal	$	63,459		$	63,459
Less: debt discount, net of amortization		(258	)		(349	)
Net carrying amount	$	63,201		$	63,110

The following table sets forth total interest expense recognized related to the 2024 Notes (in thousands):


	Three Months Ended March 31,
	2024		2023
0.125% coupon	$	20	$	42
Amortization of debt discount and transaction costs		91		190
	$	111	$	232

The effective interest rates on the 2024 Notes were 0.7% during both the three months ended March 31, 2024 and 2023.

The fair value of the 2024 Notes, which was determined based on inputs that are observable in the market or that could be derived from, or corroborated with, observable market data, quoted price of the 2024 Notes in an over-the-counter market (Level 2), and carrying value of debt instruments were as follows (in thousands):


	As of March 31, 2024				As of December 31, 2023
	Fair Value		Carrying Value		Fair Value		Carrying Value
2024 Notes	$	61,873	$	63,201	$	58,670	$	63,110

In connection with the issuance of the 2024 Notes, the Company entered into capped call transactions with certain option counterparties (the “2024 capped call transactions”). The 2024 capped call transactions are expected generally to reduce potential dilution to the Company’s common stock upon any conversion of the 2024 Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted 2024 Notes, as the case may be, with such reduction and/or offset subject to a cap. Under the 2024 capped call transactions, the Company purchased capped call options that in the aggregate relate to the total number of shares of the Company’s common stock underlying the 2024 Notes, with an initial strike price of approximately $112.36 per share, which corresponds to the initial conversion price of the 2024 Notes and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of the 2024 Notes, and with a cap price of approximately $166.46. The cost of the purchased capped calls of $44.9 million was recorded to shareholders’ equity and will not be re-measured.

Based on the closing price of the Company’s common stock of $34.83 on March 31, 2024, the if-converted value of the 2024 Notes was less than their respective principal amounts.

The following table summarizes the Company’s debt obligations as of March 31, 2024 (in thousands):


	Remainder of 2024		2025		2026		Total
Debt obligations	$	63,459	$	—	$	300,276	$	363,735

Debt obligations include the principal amount of the 2026 Notes and 2024 Notes but exclude interest payments to be made under the 2026 Notes and 2024 Notes. Although the 2026 Notes and 2024 Notes mature in 2026 and 2024, respectively, they can be converted into cash and/or shares of the Company’s common stock prior to maturity if certain conditions are met. Any conversion prior to maturity can result in repayments of the principal amounts earlier than the scheduled repayments as indicated in the table. The 2026 Notes and 2024 Notes balance excludes debt discount capitalized on the balance sheet.