On January 1, 2022, the Company adopted the new guidance for convertible instruments using a modified retrospective method. Results for reporting periods beginning after December 31, 2021 are presented under the new guidance, while prior period comparative amounts are not adjusted and continue to be reported in accordance with historical guidance.

The new guidance eliminates the bifurcation and separate recognition of the embedded cash conversion feature from the host contract and allows for the entire amount attributable to the debt to be presented as a liability. The carrying amount of the debt liability will be reduced by the issuance costs associated with the debt issuance as a contra-liability. As there is no longer an equity component of the convertible debt, the discount created by accretion of a component of the convertible debt in equity is eliminated and interest expense is reduced. The deferred tax liability recognized as a result of a difference between the carrying amount and tax basis of the 2022 Notes that was recorded to additional paid-in capital as a component of equity was also reversed. There is no change in the

accounting for the Capped Call Options, Warrants, or Convertible Note Hedges as they are classified as equity under both the historical and new guidance.

As a result of the impact of applying the new guidance, the Company recorded an increase to opening accumulated deficit of $31.4 million as of January 1, 2022, related to the difference in interest expense due to the amortization of the convertible debt discount and reversal of the deferred tax liability under the historical guidance. The resulting impact on the consolidated balance sheet to derecognize the debt issuance cost and conversion option that was allocated to the equity component and to derecognize the remaining convertible debt discount was an increase to debt liability of $69.8 million, of which $0.5 million was recorded to short term debt and $69.3 million was recorded to long-term debt, and a decrease in additional paid-in capital of $101.2 million.

In June 2020, the Company issued $400 million aggregate principal amount of 0.375% convertible senior notes due June 1, 2025 (the “2025 Notes”) in a private offering and an additional $60 million aggregate principal amount of the 2025 Notes pursuant to the exercise in full of the over-allotment options of the initial purchasers. The interest rate is fixed at 0.375% per annum and is payable semi-annually in arrears on June 1 and December 1 of each year. The total net proceeds from the debt offering, after deducting initial purchase discounts and debt issuance costs, were approximately $450.1 million.

Each $1,000 of principal amount of the 2025 Notes will initially be convertible into 3.5396 shares of the Company’s common stock (the “Conversion Option of the 2025 Notes”), which is equivalent to an initial conversion price of approximately $282.52 per share, subject to adjustment upon the occurrence of certain specified events. On or after March 1, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their 2025 Notes at any time. The 2025 Notes will be convertible at the option of the holders prior to the close of business on the business day immediately preceding March 1, 2025 under certain circumstances as described in the indenture governing the 2025 Notes (the “Indenture”). 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 the Company’s common stock, at the Company’s election. The Company expects to settle the principal amount of the 2025 Notes in cash. Because the last reported sale price of the Company’s common stock for at least 20 trading days during the period of 30 consecutive trading days ending on the last trading day of the calendar quarter ended December 31, 2023 was equal to or greater than 130% of the applicable conversion price on each applicable trading day, the 2025 Notes are convertible at the option of the holders thereof during the calendar quarter ending March 31, 2024. As of February 9, 2024, the Company has not received any material conversion notices.

In accordance with GAAP relating to the embedded conversion feature, the Company bifurcated the conversion feature associated with the 2025 Notes and recorded $96.6 million to additional paid-in capital for the conversion feature and the resulting debt discount was being amortized to interest expense. As there is no longer an equity component of the convertible debt under the new standard, the debt issuance cost and conversion option that was allocated to the equity component was derecognized through an adjustment to opening retained earnings upon adoption of the new standard on January 1, 2022.

The net carrying amount of the liability component of the 2025 Notes is as follows:


	As of December 31, 2023			As of December 31, 2022
	(in thousands)
Principal	$	459,076		$	459,083
Unamortized issuance costs		(2,870	)		(4,856	)
Net carrying amount	$	456,206		$	454,227

Interest expense related to the 2025 Notes is as follows:


	Year Ended December 31,
	2023		2022		2021
	(in thousands)
Contractual interest expense	$	1,722	$	1,722	$	1,725
Amortization of debt discount		—		—		18,171
Amortization of issuance costs		1,986		1,969		1,428
Total interest expense	$	3,708	$	3,691	$	21,324

In connection with the offering of the 2025 Notes, the Company purchased capped call options (“Capped Call Options”) with respect to its common stock for $50.6 million. The Capped Call Options are purchased call options that give the Company the option

to purchase up to approximately 1.6 million shares of its common stock for $282.52 per share, which corresponds to the approximate initial conversion price of the 2025 Notes. The Capped Call Options were purchased in order to offset potential dilution to the Company’s common stock upon any conversion of the 2025 Notes, subject to a cap of $426.44 per share, and expire concurrently with the 2025 Notes. The Capped Call Options automatically settle in components commencing on April 16, 2025 and are subject to either adjustment or termination upon the occurrence of specified extraordinary events affecting the Company, including a merger event; a tender offer; and a nationalization, insolvency or delisting involving the Company. In addition, the Capped Call Options are subject to certain specified additional disruption events that may give rise to a termination of the Capped Call Options, including changes in law, insolvency filings, and hedging disruptions. Since the transaction meets certain accounting criteria, the $50.6 million paid for the Capped Call Options is recorded in stockholders’ equity as a reduction in additional paid-in capital and are not accounted for as separate derivative financial instruments.

In May 2017, the Company issued $350.0 million aggregate principal amount of 0.25% convertible senior notes due June 1, 2022 (the “2022 Notes”) in a private offering and an additional $50 million aggregate principal amount of such notes pursuant to the exercise in full of the over-allotment options of the initial purchasers of the 2022 Notes. The interest rate is fixed at 0.25% per annum and is payable semi-annually in arrears on June 1 and December 1 of each year. The total net proceeds from the debt offering, after deducting initial purchase discounts and debt issuance costs, were approximately $389.2 million.

In connection with the offering of the 2022 Notes, the Company entered into convertible note hedge transactions (the “Convertible Note Hedges”) with certain counterparties in which the Company has the option to purchase (subject to adjustment for certain specified events) up to approximately 4.2 million shares of the Company’s common stock at a price of approximately $94.77 per share. In addition, the Company sold warrants (the “Warrants”) to certain bank counterparties whereby the holders of the Warrants have the option to initially purchase (subject to adjustment for certain specified events) a total of approximately 4.2 million shares of the Company’s common stock at a price of $115.8 per share.

On June 1, 2022, upon the maturity of the 2022 Notes, the Company paid $19.4 million to satisfy the aggregate principal amount due and $60.4 million for the conversion premium in excess of the principal amount. The remaining Convertible Note Hedges were settled in cash and the Company received approximately $60.5 million in cash upon settlement. In addition, the remaining 1.4 million shares of Warrants were exercised in the fourth quarter of 2022, which the Company net share settled and issued 0.8 million shares of its common stock.

Interest expense related to the 2022 Notes is as follows:


	Year Ended December 31,
	2023		2022		2021
	(in thousands)
Contractual interest expense	$	—	$	20	$	154
Amortization of debt discount		—		—		3,636
Amortization of issuance costs		—		44		272
Total interest expense	$	-	$	64	$	4,062