December 31, | |||||||||
2015 | 2016 | 2017 | |||||||
Dividend yield (%) | — | — | — | ||||||
Expected volatility (%) | 68 - 70 | 63 - 69 | 63 - 64 | ||||||
Risk–free interest rate (%) | 0.34 - 0.87 | 0.00 - 0.47 | 0.43 | ||||||
Assumed annual lapse rate of awards (%) | 10 | 10 (5 for RSA) | 10 for RSA 2 for stock options, warrants and a limited group of beneficiaries | ||||||
Sell price multiple (applied to exercise price) | 2 | 2 | 2 | ||||||
Weighted average share price (€) | 1.59 | 1.76 | 2.30 | ||||||
Model used | Binomial | Binomial | Binomial |