NET LOSS PER COMMON SHARE

12 Months Ended

Dec. 31, 2015

(15) NET LOSS PER COMMON SHARE

Potentially issuable shares of common stock include shares issuable upon the exercise of outstanding employee stock option awards, common stock issuable under the ESPP, unvested restricted stock, common stock held by the NQDC Plan and contingent issuances of common stock related to convertible debt. The table below presents potential shares of common stock that were excluded from the computation as they were anti-dilutive using the treasury stock method (in thousands):

	Years Ended December 31,
	2015		2014		2013
Options to purchase common stock		10,323		11,477		13,157
Common stock issuable under the 2017 Notes		1,544		1,992		3,047
Common stock issuable under the 2018 and 2020 Notes		7,966		7,966		7,966
Unvested restricted stock units		1,743		1,244		1,159
Potentially issuable common stock for the ESPP purchases		180		195		197
Common stock held by the NQDC		243		224		193
Total number of potentially issuable shares		21,999		23,098		25,719

The effect of the Notes was excluded from the diluted net loss per common share since they may be settled in cash or shares at the Company’s option and the Company’s current intention is to settle up to the principal amount of the converted notes in cash and any excess conversion value (conversion spread) in shares of the Company’s common stock. Although the Company’s stock price exceeded the conversion price $94.15 at December 31, 2015, the potential shares issuable under the Notes were excluded from the calculation of diluted loss per share as they were anti-dilutive using the if-converted method. During the years ended December 31, 2014 and 2013 the Notes had no effect on diluted net loss per share as the Company’s stock price did not exceed the conversion price of $94.15 per share for the Notes.