On July 19, 2019, the Company issued $287.5 million aggregate principal pursuant to the 2019 Notes, which includes the underwriters’ exercise in full of an option to purchase an additional $37.5 million aggregate principal amount of 2019 Notes (the “Notes Offering”). The net proceeds of the Notes Offering, after deducting underwriting discounts and commissions and other related offering expenses payable by the Company, were approximately $278.5 million. The 2019 Notes are senior, unsecured obligations of the Company, and bear interest at a rate of 0.375% per year. Interest is payable semi-annually in arrears on January 15 and July 15 of each year, beginning on January 15, 2020. The 2019 Notes will mature on July 15, 2024, unless earlier repurchased or converted in accordance with their terms.

During the first quarter of 2022, the closing price of the Company’s common stock exceeded 130% of the conversion price of the 2019 Notes for more than 20 trading days of the last 30 consecutive trading days of the quarter. As a result, the 2019 Notes are convertible at the option of the holders of the 2019 Notes during the second quarter of 2022, the quarter immediately following the quarter when the conditions are met, as stated in the terms of the 2019 Notes. These conditions have been met since the fourth quarter of 2020. As a result, $15,000 in aggregate principal amount of the 2019 Notes have been converted by the noteholders since the issuance of the 2019 Notes, including $4,000 during the first quarter of 2022. The conversions resulted in the issuance of a nominal number of shares of the Company’s common stock to the note holders. The Company continues to classify the carrying value of the 2019 Notes as current liabilities on the Company’s consolidated balance sheet at March 31, 2022.

Prior to the adoption of ASU 2020-06, the Company accounted for the 2019 Notes as a liability and equity component where the carrying value of the liability component was valued based on a similar debt instrument. In accounting for the issuance of the 2019 Notes, the Company separated the 2019 Notes into liability and equity components. The carrying value of the liability component was calculated as the present value of its cash flows using a discount rate of 4.5% based on comparative convertible transactions for similar companies. The carrying value of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the 2019 Notes as a whole. The excess of the principal amount of the liability component over its carrying value amount, referred to as the debt discount, was amortized to interest expense on our consolidated statements of comprehensive income over the five-year term of the 2019 Notes. The equity component was not re-measured as long as it continued to meet the conditions for equity classification. The equity component recorded at issuance related to the 2019 Notes was $52.1 million, which was recorded in additional paid-in capital in our consolidated balance sheets.

In accounting for the transaction costs related to the issuance of the 2019 Notes, the Company allocated the total costs incurred to the liability and equity components of the 2019 Notes using the same proportions as the initial carrying value of the 2019 Notes. Transaction costs related to the liability component were $7.4 million and are amortized to interest expense using the effective interest method over the five-year term of the 2019 Notes. Transaction costs attributable to the equity component were $1.6 million and are netted with the equity component of the 2019 Notes in stockholders' equity of the Company's consolidated balance sheet. Additionally, the Company recorded a net deferred tax liability of $11.4 million.

Effective January 1, 2022, the Company adopted ASU 2020-06. After adoption, the Company now accounts for the 2019 Notes as a single liability measured at amortized cost. As the equity component is no longer required to be split into a separate component, the Company recorded a net adjustment for the initial $50.4 million that was allocated to additional paid-in capital and $22.9 million of life-to-date interest expense recorded as amortization of debt discount. Additionally, the net deferred tax liability recorded for the 2019 Notes was reversed. The principal amount of the liability over its carrying amount is amortized to interest expense over the five-year term of the 2019 Notes. Since the 2019 Notes are classified as a single liability, there is no debt discount required to be amortized for the three months ended March 31, 2022.

The net carrying value of the liability component of the 2019 Notes is as follows:


	March 31,			December 31,
	2022			2021
	(Amounts in thousands)
0.375% convertible senior notes due 2024:
Principal amount	$	287,485		$	287,489
Unamortized debt discount		—			(28,220	)
Unamortized debt issuance costs		(4,218	)		(4,011	)
Net carrying amount	$	283,267		$	255,258

The following table sets forth total interest expense recognized related to the 2019 Notes:


	Three Months Ended
	March 31,
	2022			2021
	(Amounts in thousands)
Contractual interest expense	$	270		$	270
Amortization of debt issuance costs		452			352
Amortization of debt discount		—			2,478
Total	$	722		$	3,100
Effective interest rate of the liability component		0.3	%		1.2	%

At March 31, 2022 and December 31, 2021, the carrying value of the 2019 Notes was $283.3 million and $255.3 million, respectively, net of unamortized discount, and the fair value of the 2019 Notes was $490.2 million and $678.5 million, respectively. The fair value of the 2019 Notes was determined based on the most recent trade activity of the 2019 Notes at March 31, 2022 and December 31, 2021.