8. CONVERTIBLE NOTES, NET

As of September 30, 2018, the following convertible senior notes, or Convertible Notes, were outstanding ($ in thousands):


Convertible Notes Issuance	Face Value		Coupon Rate			All-in Cost⁽¹⁾			Conversion Rate⁽²⁾		Maturity
November 2013	$	172,328		5.25	%		5.87	%		36.5472		December 1, 2018
May 2017		402,500		4.38	%		4.85	%		28.0324		May 5, 2022
March 2018		220,000		4.75	%		5.33	%		27.6052		March 15, 2023


(1)		Includes issuance costs that are amortized through interest expense over the life of the Convertible Notes using the effective interest method.
(2)		Represents the shares of class A common stock per $1,000 principal amount of Convertible Notes, which is equivalent to a conversion price of $27.36, $35.67, and $36.23 per share of class A common stock, respectively, for the November 2013, May 2017, and March 2018 convertible notes. As a result of exceeding the cumulative dividend threshold, as defined in the November 2013 convertible notes supplemental indenture, the conversion rate on the November 2013 convertible notes was most recently adjusted on March 28, 2018 from the prior conversion rate of 36.1380 shares of class A common stock per $1,000 principal amount of convertible notes, which was equivalent to a conversion price of $27.67 per share of class A common stock. Pursuant to the terms of the November 2013 supplemental indenture, the conversion rate will be adjusted to 36.8161 on the first day of any future observation period related to a conversion of the November 2013 convertible notes to account for the dividends paid on our class A common stock on July 16, 2018 and October 15, 2018. The cumulative dividend threshold as defined in the respective May 2017 and March 2018 convertible notes supplemental indentures have not been exceeded as of September 30, 2018.

The Convertible Notes are convertible at the holders’ option into shares of our class A common stock, only under specific circumstances, prior to the close of business on August 31, 2018, January 31, 2022, and December 14, 2022 for the November 2013, May 2017, and March 2018 convertible notes, respectively, at the applicable conversion rate in effect on the conversion date. Thereafter, the Convertible Notes are convertible at the option of the holder at any time until the second scheduled trading day immediately preceding the maturity date. We may not redeem the Convertible Notes prior to maturity. The last reported sale price of our class A common stock of $33.51 on September 28, 2018, the last trading day in the quarter ended September 30, 2018, was greater than the per share conversion price of the November 2013 convertible notes but less than the per share conversion price of the May 2017 and March 2018 convertible notes. We have the intent and ability to settle each series of the Convertible Notes in cash and, as a result, the Convertible Notes did not have any impact on our diluted earnings per share. During the nine months ended September 30, 2018, holders of $172,000 of our November 2013 convertible notes elected to convert their notes pursuant to the terms of the November 2013 convertible notes supplemental indenture. The conversions were settled entirely in cash.

Upon our issuance of the November 2013 convertible notes, we recorded a $9.1 million discount based on the implied value of the conversion option and an assumed effective interest rate of 6.50%, as well as $4.1 million of initial issuance costs. Including the amortization of this discount and the issuance costs, our total cost of the November 2013 convertible notes issuance is 7.16% per annum.

Upon our issuance of the May 2017 convertible notes, we recorded a $979,000 discount based on the implied value of the conversion option and an assumed effective interest rate of 4.57%, as well as $8.4 million of initial debt discount and issuance costs. Including the amortization of the discount and issuance costs, our total cost of the May 2017 convertible notes issuance is 4.91% per annum.

Upon our issuance of the March 2018 convertible notes, we recorded a $1.5 million discount based on the implied value of the conversion option and an assumed effective interest rate of 5.25%, as well as $5.2 million of initial debt discount and issuance costs. Including the amortization of the discount and issuance costs, our total cost of the March 2018 convertible notes issuance is 5.49% per annum.

The following table details the net book value of our Convertible Notes on our consolidated balance sheets ($ in thousands):


	September 30, 2018			December 31, 2017
Face value	$	794,828		$	575,000
Unamortized discount		(12,956	)		(10,279	)
Deferred financing costs		(921	)		(810	)

Net book value	$	780,951		$	563,911

The following table details our interest expense related to the Convertible Notes ($ in thousands):


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Cash coupon	$	9,277	$	6,247	$	25,333	$	12,732
Discount and issuance cost amortization		1,535		1,202		4,242		2,869

Total interest expense	$	10,812	$	7,449	$	29,575	$	15,601

Accrued interest payable for the Convertible Notes was $10.8 million and $3.7 million as of September 30, 2018, and December 31, 2017, respectively. Refer to Note 2 for additional discussion of our accounting policies for the Convertible Notes.