Net loss per common share

12 Months Ended

Dec. 31, 2015

12. Net loss per common share

Basic net loss per share excludes dilution for potentially dilutive securities and is computed by dividing net loss by the weighted average number of common shares outstanding during the period excluding the 9,000,000 shares loaned to Bank of America under a share lending arrangement (see Note 11 — Common and preferred stock). In the third quarter of 2015, the 9,000,000 million shares loaned to Bank of America were returned. Prior to the return of those shares, the borrowed shares were not considered outstanding for the purpose of computing and reporting basic or diluted earnings (loss) per share because the share borrower had to return all borrowed shares to the Company (or, in certain circumstances, the cash value thereof). Diluted net loss per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock. Potentially dilutive securities are excluded from the computation of diluted net loss per share for all of the periods presented in the accompanying condensed consolidated statements of operations because the reported net loss in each of these periods results in their inclusion being antidilutive. Antidilutive securities, which consist of stock options, restricted stock units, warrants, and shares that could be issued upon conversion of the senior convertible notes, that are not included in the diluted net loss per share calculation and excluded the 9,000,000 shares of the Company’s common stock loaned under the share lending arrangement as of December 31, 2014, and 2013.

Potentially dilutive securities outstanding are summarized as follows (in shares):


	December 31,
	2015		2014		2013
Exercise of common stock options		19,779,229		21,541,664		24,237,940
Conversion of senior convertible notes into common stock		4,072,809		17,323,080		25,415,366
Exercise of common stock warrants		4,074,596		9,987,876		19,706,240
Vesting of restricted stock units		1,804,620		2,610,720		9,115,821

		29,731,254		51,463,340		78,475,367