11. Income / loss (-) per share

Basic income / loss (-) per share is calculated by dividing the net income / loss (-) attributable to shareholders by the weighted average number of ordinary shares issued during the year.

Diluted income / loss (-) per share is calculated based on the weighted average number of shares (diluted) also considering outstanding warrants, for which our average share price of the year was higher than the exercise price.

Income / loss (-) per share


	Year ended December 31,
	2017		2016		2015
Income / loss (-) per share:
Net income / loss (-) attributable to owners of the parent (Euro, in thousands )	€	(115,704)	€	54,012	€	(118,410)
Number of shares (thousands)
Weighted average number of shares for the purpose of basic income / loss (-) per share		49,479		45,696		35,700
Basic income / loss (-) per share (Euros)	€	(2.34)	€	1.18	€	(3.32)

Net income / loss (-) attributable to owners of the parent (Euro, in thousands )	€	(115,704)	€	54,012	€	(118,410)
Number of shares (thousands)
Weighted average number of shares for the purpose of diluted income / loss (-) per share		49,479		45,696		35,700
Number of dilutive potential ordinary shares		—		1,612		—
Diluted income / loss (-) per share (Euros)	€	(2.34)	€	1.14	€	(3.32)

As our operations reported a net loss in 2015 and 2017, the outstanding warrants (specified in note 29) have an anti-dilutive effect rather than a dilutive effect. Consequently, basic and diluted loss per share were the same for 2015 and 2017.

Basic income per share of €1.18 and diluted income per share of €1.14 in 2016 are based on a net income for 2016 which was strongly influenced by the non-cash gain from the fair value re-measurement of the share subscription agreement with Gilead amounting to €57.5 million.