6. Indebtedness

The carrying values of the Company’s Senior Convertible Notes are as follows:

(in thousands)	June 30, 2016			December 31, 2015
2.75% Senior Convertible Notes due 2017:
Principal amount	$	125,732		$	402,500
Unamortized debt discount		(5,508	)		(25,958	)
Unamortized debt issuance costs		(773	)		(3,622	)
		119,451			372,920
2.25% Senior Convertible Notes due 2021:
Principal amount		650,000			—
Unamortized debt discount		(80,403	)		—
Unamortized debt issuance costs		(14,104	)		—
		555,493			—
Total Senior Convertible Notes	$	674,944		$	372,920

Less Current Portion:		(119,451	)		—
Long-term Senior Convertible Notes	$	555,493		$	372,920

2.25% Senior Convertible Notes due 2021

In March 2016, the Company issued $650.0 million principal amount of unsecured Senior Convertible Notes with a stated interest rate of 2.25% and a maturity date of March 15, 2021 (the "2021 Notes"). The net proceeds from the offering, after deducting initial purchasers' discounts and costs directly related to the offering, were approximately $634.1 million. The 2021 Notes may be settled in cash, stock, or a combination thereof, solely at the Company's discretion. It is the Company's current intent and policy to settle all conversions through combination settlement, which involves satisfying the principal amount outstanding with cash and any note conversion value over the principal amount in shares of the Company's common stock. The initial conversion rate of the 2021 Notes is 16.7158 shares per $1,000 principal amount, which is equivalent to a conversion price of approximately $59.82 per share, subject to adjustments. The Company uses the treasury share method for assumed conversion of the 2021 Notes to compute the weighted average shares of common stock outstanding for diluted earnings per share. The Company also entered into transactions for convertible note hedge (the "2021 Hedge") and warrants (the "2021 Warrants") concurrently with the issuance of the 2021 Notes.

The cash conversion feature of the 2021 Notes required bifurcation from the Notes and was initially accounted for as an equity instrument classified to stockholders’ equity, which resulted in recognizing $84.8 million in additional paid-in-capital during 2016.

The interest expense recognized on the 2021 Notes during the three months ended June 30, 2016 includes $3.7 million, $3.7 million and $0.6 million for the contractual coupon interest, the accretion of the debt discount and the amortization of the debt issuance costs, respectively. The interest expense recognized on the 2021 Notes during the six months ended June 30, 2016 includes $4.3 million, $4.4 million and $0.7 million for the contractual coupon interest, the accretion of the debt discount and the amortization of the debt issuance costs, respectively. The effective interest rate on the 2021 Notes is 5.8%, which includes the interest on the notes, amortization of the debt discount and debt issuance costs. Interest on the 2021 Notes began accruing upon issuance and is payable semi-annually.

Prior to September 15, 2020, holders may convert their 2021 Notes only under the following conditions: (a) during any calendar quarter beginning June 30, 2016, if the reported sale price of the Company's common stock for at least 20 days out of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (b) during the five business day period in which the trading price of the 2021 Notes falls below 98% of the product of (i) the last reported sale price of the Company's common stock and (ii) the conversion rate on that date; and (c) upon the occurrence of specified corporate events, as defined in the 2021 Notes. From September 15, 2020 and until the close of business on the second scheduled trading day immediately preceding March 15, 2021, holders may convert their 2021 Notes at any time (regardless of the foregoing circumstances). The Company may not redeem the 2021 Notes prior to March 20, 2019. The Company may redeem the 2021 Notes, at its option, in whole or in part on or after March 20, 2019 until the close of business on the business day immediately preceding September 15, 2020 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 during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company delivers written notice of a redemption. The redemption price will be equal to 100% of the principal amount of such 2021 Notes to be redeemed plus accrued and unpaid interest to, but excluding, the redemption date. No principal payments are due on the 2021 Notes prior to maturity. Other than restrictions relating to certain fundamental changes and consolidations, mergers or asset sales and customary anti-dilution adjustments, the 2021 Notes do not contain any financial covenants and do not restrict the Company from paying dividends or issuing or repurchasing any of its other securities. The Company is unaware of any current events or market conditions that would allow holders to convert the 2021 Notes.

2021 Hedge

In connection with the offering of the 2021 Notes, the Company entered into the hedge transaction with the initial purchasers and/or their affiliates (the "2021 Counterparties") entitling the Company to purchase up to 10,865,270 shares of the Company's common stock at an initial stock price of $59.82 per share, each of which is subject to adjustment. The cost of the 2021 Hedge was $111.2 million and accounted for as an equity instrument by recognizing $111.2 million in additional paid-in-capital during 2016. The 2021 Hedge will expire on March 15, 2021. The 2021 Hedge is expected to reduce the potential equity dilution upon conversion of the 2021 Notes if the daily volume-weighted average price per share of the Company's common stock exceeds the strike price of the 2021 Hedge. An assumed exercise of the 2021 Hedge by the Company is considered anti-dilutive since the effect of the inclusion would always be anti-dilutive with respect to the calculation of diluted earnings per share.

2021 Warrants

The Company sold warrants to the 2021 Counterparties to acquire up to 10,865,270 shares of the Company’s common stock. The 2021 Warrants will expire on various dates from June 2021 through December 2021 and may be settled in cash or net shares. It is the Company's current intent and policy to settle all conversions in shares of the Company’s common stock. The Company received $44.9 million in cash proceeds from the sale of the 2021 Warrants, which was recorded in additional paid-in-capital. The 2021 Warrants could have a dilutive effect on the Company's earnings per share to the extent that the price of the Company's common stock during a given measurement period exceeds the strike price of the 2021 Warrants, which is $80.00 per share. The Company uses the treasury share method for assumed conversion of its 2021 Warrants to compute the weighted average common shares outstanding for diluted earnings per share.

2.75% Senior Convertible Notes due 2017

In June 2011, the Company issued $402.5 million principal amount of Senior Convertible Notes with a stated interest rate of 2.75% and a maturity date of July 1, 2017 (the “2017 Notes”). The net proceeds from the offering, after deducting initial purchasers’ discounts and costs directly related to the offering, were approximately $359.2 million. The 2017 Notes may be settled in cash, stock, or a combination thereof, solely at the Company’s discretion. It is the Company’s current intent and policy to settle all conversions through combination settlement, which involves satisfying the principal amount outstanding with cash and any note conversion value over the principal amount in shares of the Company’s common stock. The initial conversion rate of the 2017 Notes is 23.7344 shares per $1,000 principal amount, which is equivalent to a conversion price of approximately $42.13 per share, subject to adjustments. The Company uses the treasury share method for assumed conversion of the 2017 Notes to compute the weighted average shares of common stock outstanding for diluted earnings per share. The Company also entered into transactions for convertible note hedge (the “2017 Hedge”) and warrants (the “2017 Warrants”) concurrently with the issuance of the 2017 Notes. In March 2016, the Company used approximately $345.2 million of the net proceeds from the 2021 Notes offering to repurchase approximately $276.8 million in principal amount outstanding of the $402.5 million 2017 Notes. The repurchase of a portion of the 2017 Notes resulted in a remaining balance of $125.7 million principal amount outstanding. For more details, refer to “Repurchase of Senior Convertible Notes due 2017”.

The cash conversion feature of the 2017 Notes required bifurcation from the Notes and was initially accounted for as a derivative liability and debt discount of $88.9 million upon issuance of the Notes without authorization of issuing additional common stocks for the conversion. Upon obtaining stockholder approval for the additional authorized shares of the Company’s common stock, the derivative liability was reclassified to stockholders’ equity, which resulted in recognizing cumulatively $39.5 million in other income for change in fair value measurement and $49.4 million in additional paid-in-capital during 2011.

The interest expense recognized on the 2017 Notes during the three months ended June 30, 2016 includes $0.9 million, $1.3 million and $0.2 million for the contractual coupon interest, the accretion of the debt discount and the amortization of debt issuance costs, respectively. The interest expense recognized on the 2017 Notes during the six months ended June 30, 2016 includes $3.3 million, $5.0 million and $0.7 million for the contractual coupon interest, the accretion of the debt discount and the amortization of the debt issuance costs, respectively. During the three months ended June 30, 2015, interest expense recognized on the 2017 Notes includes $2.8 million, $3.9 million and $0.5 million for the contractual coupon interest, the accretion of the debt discount, and the amortization of the debt issuance costs, respectively. The interest expense recognized on the 2017 Notes during the six months ended June 30, 2015 includes $5.5 million, $7.8 million and $1.0 million for the contractual coupon interest, the accretion of the debt discount and the amortization of debt issuance costs, respectively. The effective interest rate on the 2017 Notes is 8.0%, which includes the interest on the notes, amortization of the debt discount and debt issuance costs. Interest on the 2017 Notes began accruing upon issuance and is payable semi-annually.

Prior to January 1, 2017, holders may convert their 2017 Notes only under the following conditions: (a) during any calendar quarter beginning October 1, 2011, if the reported sale price of the Company’s common stock for at least 20 days out of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (b) during the five business day period in which the trading price of the 2017 Notes falls below 98% of the product of (i) the last reported sale price of the Company’s common stock and (ii) the conversion rate on that date; and (c) upon the occurrence of specified corporate events, as defined in the 2017 Notes. From January 1, 2017 and until the close of business on the second scheduled trading day immediately preceding July 1, 2017, holders may convert their 2017 Notes at any time (regardless of the foregoing circumstances). The Company may not redeem the 2017 Notes prior to maturity. Other than restrictions relating to certain fundamental changes and consolidations, mergers or asset sales and customary anti-dilution adjustments, the 2017 Notes do not contain any financial covenants and do not restrict the Company from paying dividends or issuing or repurchasing any of its other securities. At June 30, 2016, holders of the 2017 Notes were in a convertible position, as the reported sale price of the Company’s common stock for 20 days out of the last 30 consecutive trading days ending with June 30, 2016 exceeded 130% of the $42.13 per share conversion price on each applicable trading day. At June 30, 2016, no holders of the 2017 Notes elected to convert. The Company reclassified the 2017 Notes to current liabilities on the June 30, 2016 consolidated balance sheet.

2017 Hedge

In connection with the offering of the 2017 Notes, the Company entered into the 2017 Hedge with the initial purchasers and/or their affiliates (the “2017 Counterparties”) entitling the Company to purchase up to 9,553,096 shares of the Company’s common stock at an initial stock price of $42.13 per share, each of which is subject to adjustment. The cost of the 2017 Hedge was $80.1 million and accounted for as derivative assets upon issuance of the 2017 Notes. Upon obtaining stockholder approval for the additional authorized shares of the Company’s common stock, the derivative asset was reclassified to stockholders’ equity, which resulted in recognizing cumulatively $37.1 million in other expense for the change in fair value measurement and $43.0 million in additional paid-in-capital during 2011. The 2017 Hedge will expire on July 1, 2017. The 2017 Hedge is expected to reduce the potential equity dilution upon conversion of the 2017 Notes if the daily volume-weighted average price per share of the Company’s common stock exceeds the strike price of the 2017 Hedge. An assumed exercise of the 2017 Hedge by the Company is considered anti-dilutive since the effect of inclusion would always be anti-dilutive with respect to the calculation of diluted earnings per share.

2017 Warrants

The Company sold warrants to the 2017 Counterparties to acquire up to 477,654 shares of the Company’s Series A Participating Preferred Stock at an initial strike price of $988.51 per share, subject to adjustment. Each share of Series A Participating Preferred Stock is convertible into 20 shares of the Company’s common stock, or up to 9,553,080 common shares in total. The 2017 Warrants will expire on various dates from September 2017 through January 2018 and may be settled in cash or net shares. It is the Company’s current intent and policy to settle all conversions in shares of the Company’s common stock. The Company received $47.9 million in cash proceeds from the sale of the 2017 Warrants, which was recorded in additional paid-in-capital. The 2017 Warrants could have a dilutive effect on the Company’s earnings per share to the extent that the price of the Company’s common stock during a given measurement period exceeds the strike price of the 2017 Warrants. The Company uses the treasury share method for assumed conversion of its 2017 Warrants to compute the weighted average common shares outstanding for diluted earnings per share.

Repurchases of Senior Convertible Notes due 2017

In March 2016, the Company used approximately $345.2 million of the net proceeds from the 2021 Notes offering to repurchase approximately $276.8 million principal amount outstanding of the $402.5 million principal Senior Convertible Notes due 2017, the associated conversion feature of the repurchased notes (which is recorded in additional paid-in capital), and the accrued interest on the repurchased notes. As a result of this repurchase, the Company recorded a loss in other expense on the accompanying Consolidated Statements of Operations for the six months ended June 30, 2016 of approximately $17.4 million for the early extinguishment of 2017 Notes and the related debt issuance costs that were previously capitalized in connection with the issuance of the 2017 Notes. The repurchase of a portion of the 2017 Notes resulted in remaining balances of $125.7 million, $6.8 million, and $1.0 million of principal outstanding, debt discount, and debt issuance costs, respectively, at the time of the repurchase. The Company intends to use the remainder of the net proceeds from the 2021 Notes offering for general corporate purposes.

Revolving Senior Credit Facility

In February 2016, the Company entered into a Credit Agreement (the “Credit Agreement”) for a revolving senior credit facility (the “Facility”) that provides for secured revolving loans, multicurrency loan options and letters of credit in an aggregate amount of up to $150.0 million. The Credit Agreement also contains an expansion feature, which allows the Company to increase the aggregate principal amount of the Facility provided the Company remains in compliance with the underlying financial covenants. The Facility matures February 8, 2021, and includes a sub-limit of $15.0 million for letters of credit and a sub-limit of $5.0 million for swing line loans. All assets of the Company and its material domestic subsidiaries are pledged as collateral under the Facility (subject to customary exceptions) pursuant to the term set forth in the Security and Pledge Agreement (the “Security Agreement”) executed in favor of the administrative agent by the Company. Each of the Company’s material domestic subsidiaries guarantees the Facility. At June 30, 2016 the Company does not carry any outstanding revolving loans under the Facility.

Borrowings under the Facility are used by us to provide financing for working capital and other general corporate purposes, including potential mergers and acquisitions. Loans under the Facility bear interest, at the option of the Company, at either LIBOR (determined in accordance with the Credit Agreement) plus an applicable margin ranging from 1.00 % - 2.00 % per annum subject to Company’s applicable consolidated leverage ratio or the Base Rate (determined in accordance with the Credit Agreement), plus an applicable margin ranging from 0.0% - 1.25% per annum subject to Company’s applicable consolidated leverage ratio. The Facility has a commitment fee, which accrues at a rate of 0.2% - 0.4% per annum (determined in accordance with the Credit Agreement) based on the Company’s current leverage ratio.

The Credit Agreement contains affirmative, negative and financial covenants, and events of default customary for financings of this type. The financial covenants require the Company to maintain ratios of consolidated earnings before interest, taxes, depreciation and amortization (EBITDA) in relation to consolidated interest expense and consolidated debt, respectively, as defined in the Credit Agreement, at varying scales throughout the life of the Credit Agreement. The Facility grants the lenders preferred first priority liens and security interests in capital stock, intercompany debt and all of the present and future property and assets of the Company and each guarantor.