Long-Term Debt

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Long-Term Debt

Long-Term Debt

The Company’s long-term debt consisted of the following (in thousands):

	December 31,
	2023		2022
Current portion:
3.75% Convertible notes due 2023	$	—	$	325,000
Unamortized debt issuance costs	—		(119)
Total current convertible notes payable	$	—	$	324,881
Non-current portion:
5.00% Convertible notes due 2027	$	175,250	$	175,250
Unamortized debt issuance costs	(7,234)		(8,784)
Total non-current convertible notes payable	$	168,016	$	166,466

Interest expense incurred in connection with the convertible notes payable consisted of the following (in thousands):

	Year Ended December 31,
	2023		2022		2021
Coupon interest	$	9,779	$	12,542	$	12,188
Amortization of debt issuance costs	1,689		1,497		1,424
Total interest expense on convertible notes payable	$	11,468	$	14,039	$	13,612

2027 Convertible Notes

In December 2022, the Company issued $175.3 million aggregate principal amount of convertible senior unsecured notes that will mature on December 15, 2027 (the “2027 Notes”), unless earlier converted, redeemed, or repurchased. The 2027 Notes were issued in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended, and pursuant to an indenture dated December 20, 2022 (the “2027 Indenture”) between the Company and The Bank of New York Mellon Trust Company, N.A., as trustee. Concurrently with the issuance of the 2027 Notes, the Company completed a public offering of shares of its common stock (see Note 11). The Company received $166.4 million in net proceeds from the issuance of the 2027 Notes after deducting the initial purchasers’ fees and the Company’s offering expenses. The 2027 Notes bear cash interest at a rate of 5.00% per year, payable semiannually in arrears on June 15 and December 15 of each year, beginning on June 15, 2023.

The 2027 Notes are convertible at the option of the holders at any time prior to the close of business on the business day immediately preceding September 15, 2027, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2023 (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 conversion price for the 2027 Notes on each applicable trading day; (2) during the five business day period after any ten consecutive trading day period (the “measurement period”) in which the trading price (as defined in the 2027 Indenture) per $1,000 principal amount of the 2027 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 conversion rate for the 2027 Notes on each such trading day; (3) if the Company calls such 2027 Notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date, but only with respect to the 2027 Notes called (or deemed called) for redemption; and (4) upon the occurrence of specified corporate events as set forth in the 2027 Indenture. On or after September 15, 2027, until the close of business on the business day immediately preceding the maturity date (December 15, 2027), holders of the 2027 Notes may convert all or any portion of their 2027 Notes at any time, regardless of the foregoing conditions. Upon conversion, the Company may satisfy its conversion obligation by paying or delivering, as the case may be, cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, in the manner and subject to the terms and conditions provided in the 2027 Indenture.

The conversion rate for the 2027 Notes will initially be 80.0000 shares of the Company’s common stock per $1,000 principal amount of 2027 Notes, which is equivalent to an initial conversion price of $12.50 per share of common stock. The initial conversion price of the 2027 Notes represents a conversion premium of 25% of the public offering price in the Company’s concurrent common stock offering that closed on December 20, 2022 (see Note 11). The conversion rate for the 2027 Notes is subject to adjustment under certain circumstances in accordance with the terms of the 2027 Indenture. In addition, following certain corporate events that occur prior to the maturity date of the 2027 Notes or if the Company delivers a notice of redemption in respect of the 2027 Notes, the Company will, under certain circumstances, increase the conversion rate of the 2027 Notes for a holder who elects to convert its 2027 Notes (or any portion thereof) in connection with such a corporate event or convert its 2027 Notes called (or deemed called) for redemption during the related redemption period (as defined in the 2027 Indenture), as the case may be.

The Company may not redeem the 2027 Notes prior to December 22, 2025. The Company may redeem for cash all or any portion of the 2027 Notes, at its option, on or after December 22, 2025, if the last reported sale price of the common stock has been at least 130% of the conversion price for the 2027 Notes then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such 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 2027 Notes to be redeemed, plus accrued and unpaid interest, to, but excluding, the redemption date. If the Company redeems less than all the outstanding 2027 Notes, at least $50 million aggregate principal amount of 2027 Notes must be outstanding and not subject to redemption as of the date of the relevant notice of redemption. No sinking fund is provided for the 2027 Notes.

If the Company undergoes a Fundamental Change (as defined in the 2027 Indenture), holders may require, subject to certain conditions and exceptions as set forth in the 2027 Indenture, the Company to repurchase for cash all or any portion of their 2027 Notes at a Fundamental Change repurchase price equal to 100% of the principal amount of the 2027 Notes to be repurchased, plus accrued and unpaid interest, to, but excluding, the Fundamental Change repurchase date. If a holder of the 2027 Notes converted upon a Make-Whole Fundamental Change (as described in the 2027 Indenture), they may be eligible to

receive a make-whole premium through an increase to the conversion rate up to a maximum of 20.0000 shares per $1,000 principal amount of 2027 Notes (subject to other adjustments as described in the 2027 Indenture).

In accounting for the issuance of the 2027 Notes, the Company determined that the scope exceptions provided under ASC Topic 815-40, Derivatives and Hedging – Contracts in Entity’s Own Equity (“ASC 815-40”) apply to all but one of the conversion features embedded in the 2027 Notes. This remaining conversion feature, which is associated with a Fundamental Change of the Company, was determined to have a de minimis value as of December 31, 2023, and 2022.

The initial purchasers’ fees and the Company’s issuance costs related to the 2027 Notes totaled $8.8 million, which were recorded as a reduction to the 2027 Notes on the consolidated balance sheet. The $8.8 million of debt issuance costs is being amortized and recognized as additional interest expense over the five-year contractual term of the 2027 Notes using an effective interest rate of 6.2%.

2023 Convertible Notes

In 2016, the Company issued $325 million aggregate principal amount of convertible senior unsecured notes that matured on February 1, 2023 (the “2023 Notes”). The 2023 Notes were senior unsecured debt obligations and were issued at par. On January 31, 2023, the Company funded the outstanding principal amount of $325 million on the 2023 Notes, due February 1, 2023 and the indenture governing the 2023 Notes was subsequently satisfied and discharged in accordance with its terms. The Company’s related “capped call transactions” expired by their terms on January 27, 2023. The Company repaid the outstanding principal amount of $325 million together with accrued but unpaid interest on the maturity date. The repayment was funded by the issuance of the 2027 Notes and the concurrent common stock offering, as well as cash on hand.

The 2023 Notes were issued pursuant to an indenture dated January 29, 2016 (the “2023 Indenture”) between the Company and the trustee. The Company received $315.0 million in net proceeds from the offering after deducting underwriting fees and offering expenses. The 2023 Notes bore cash interest at a rate of 3.75%, payable on February 1 and August 1 of each year. The 2023 Notes were not redeemable prior to maturity and were convertible into shares of the Company’s common stock. As a result of the Company’s one-for-twenty reverse stock split in 2019 and pursuant to Section 14.04(a) of the 2023 Indenture, the 2023 Notes were initially convertible into approximately 2,385,800 shares of the Company’s common stock based on the initial conversion rate of 7.3411 shares of the Company’s common stock per $1,000 principal amount of the 2023 Notes. This represents an initial conversion price of approximately $136.20 per share of the Company’s common stock, representing an approximate 22.5% conversion premium based on the last reported sale price of the Company’s common stock of $111.20 per share on January 25, 2016. In addition, the holders of the 2023 Notes may have required the Company to repurchase the 2023 Notes at par value plus accrued and unpaid interest following the occurrence of a Fundamental Change (as described in the 2023 Indenture). If a holder of the 2023 Notes converted upon a Make-Whole Adjustment Event (as described in the 2023 Indenture), they may have been eligible to receive a make-whole premium through an increase to the conversion rate up to a maximum of 8.9928 shares per $1,000 principal amount of 2023 Notes (subject to other adjustments as described in the 2023 Indenture).

The 2023 Notes are accounted for in accordance with ASC 470-20, Debt with Conversion and Other Options (“ASC 470-20”) and ASC 815-40. Under ASC 815-40, to qualify for equity classification (or non-bifurcation, if embedded) the instrument (or embedded feature) must be both (1) indexed to the issuer’s stock and (2) meet the requirements of the equity classification guidance. Based upon the Company’s analysis, it was determined the 2023 Notes did contain embedded features indexed to its own stock, but did not meet the requirements for bifurcation, and therefore do not need to be separately accounted for as an equity component. Since the embedded conversion feature met the equity scope exception from derivative accounting, and also since the embedded conversion option did not need to be separately accounted for as an equity component under ASC 470-20, the proceeds received from the issuance of the convertible debt were recorded as a liability on the consolidated balance sheets.

In connection with the issuance of the 2023 Notes, the Company also paid $38.5 million, including expenses, to enter into privately negotiated capped call transactions with certain financial institutions (the “capped call transactions”). The capped call transactions expired by their terms on January 27, 2023. The capped call transactions were generally expected to reduce the potential dilution upon conversion of the 2023 Notes in the event that the market price per share of the Company’s common stock, as measured under the terms of the capped call transactions, was greater than the strike price of the capped call transactions, which initially corresponded to the conversion price of the 2023 Notes, and was subject to anti-dilution adjustments generally similar to those applicable to the conversion rate of the 2023 Notes. The cap price of the capped call transactions was initially $194.60 per share, which represented a premium of approximately 75% based on the last reported sale

price of the Company’s common stock of $111.20 per share on January 25, 2016, and was subject to certain adjustments under the terms of the capped call transactions. If, however, the market price per share of the Company’s common stock, as measured under the terms of the capped call transactions, exceeded the cap price, there would nevertheless have been dilution upon conversion of the 2023 Notes to the extent that such market price exceeded the cap price. The Company evaluated the capped call transactions under ASC Topic 815-10, Derivatives and Hedging – Overall and determined that they should be accounted for as a separate transaction and that the capped call transactions would be classified as an equity instrument.

The Company incurred approximately $10 million of debt issuance costs in 2016 relating to the issuance of the 2023 Notes, which were recorded as a reduction to the 2023 Notes on the consolidated balance sheet. The $10.0 million of debt issuance costs was amortized and recognized as additional interest expense over the seven-year contractual term of the 2023 Notes on a straight-line basis, which approximated the effective interest rate method. The Company also incurred $0.9 million of expenses related to the capped call transactions, which were recorded as a reduction to additional paid-in-capital.