12. 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 outstanding 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.

The possible increase in the number of shares resulting from the outstanding initial warrant B has not been included in the calculation of the diluted income per share as at December 31, 2019 because they were antidilutive.

Income/loss (-) per share


	Year ended December 31,
	2019		2018		2017
Income/loss (-) per share:
Net income/loss (-) attributable to owners of the parent (Euro, in thousands)	€	149,845	€	(29,259)	€	(115,704)
Number of shares (thousands)
Weighted average number of shares for the purpose of basic income/loss (-) per share		57,614		52,113		49,479
Basic income/loss (-) per share (Euros)	€	2.60	€	(0.56)	€	(2.34)

Net income/loss (-) attributable to owners of the parent (Euro, in thousands)	€	149,845	€	(29,259)	€	(115,704)
Number of shares (thousands)
Weighted average number of shares for the purpose of diluted income/loss (-) per share		57,614		52,113		49,479
Number of dilutive potential ordinary shares		2,498		—		—
Diluted income/loss (-) per share (Euros)	€	2.49	€	(0.56)	€	(2.34)

As our operations reported a net loss in 2018 and 2017, the outstanding warrants (specified in note 28) have an anti-dilutive effect rather than a dilutive effect. Consequently, basic and diluted loss per share were the same for 2018 and 2017.