Employee Stock Option Plans

Under the Employee Stock Option Plans (“ESOP”), stock options of the Company are granted to executives and certain employees of the Group. For options granted prior to January 1, 2016, the exercise price is equal to the fair value of the shares on grant date for employees in the United States and for U.S. citizens and fair value less 30% for the rest of the world. The value of the discount is included in the grant date fair value of the award. For options granted thereafter under these ESOP plans, the exercise price of the options is equal to the fair value of the shares on grant date for all employees. Generally, the first vesting period (13.5% – 25% of the initial grant) is up to one year from the grant date and subsequently vests at a rate of 6.25% each quarter until fully vested. The exercise price for options is payable in the EUR value of a fixed USD amount; therefore, the Group considers these awards to be USD-denominated. The options are generally granted with a term of five years.

During 2019, the Company implemented a new ESOP and Director Stock Option Plan, under which stock options of the Company are granted to executives and employees of the Group and to members of the Company’s Board of Directors, respectively. For options granted under the 2019 plans, the exercise price is equal to the fair value of the ordinary shares on grant date or equal to 150% of the fair value of the ordinary shares on grant date. The exercise price is included in the grant date fair value of the award. The options granted to participants under the 2019 programs have a first vesting period of three or eight months from date of grant and vest monthly or annually thereafter until fully vested. The options are granted with a term of five years.

Restricted Stock Unit Program

During 2019, the Company implemented a new restricted stock unit (“RSU”) program for employees and for members of its Board of Directors. Both are accounted for as equity-settled share-based payment transactions. The RSUs are measured based on the fair market value of the underlying ordinary shares on the date of grant. The RSUs granted to participants under the 2019 programs have a first vesting period of three or eight months from date of grant and vest monthly or annually thereafter until fully vested four years from date of grant. The valuation of the RSUs was consistent with the fair value of the ordinary shares.

Restricted Stock Awards and Other

In connection with an acquisition during 2017, the Group issued 61,880 restricted stock awards (“RSAs”) to certain employees of the aquiree. Vesting of the RSAs is contingent on continued employment of these employees. The awards are accounted for as equity-settled share-based payment transactions. The RSAs vest over a two- and three-year period from the acquisition date. The valuation of the RSAs was consistent with the fair value of the ordinary shares.

In connection with the acquisition of Anchor during the first quarter of 2019, the Company granted 162,320 equity instruments to certain employees of Anchor. Each instrument effectively represents one ordinary share of the Company, which will be issued to the holder upon vesting. The instruments vest annually over a four-year period from the acquisition date, and vesting of the instruments is contingent on continued employment. The instruments are accounted for as equity-settled share-based payment transactions and are measured based on the fair market value of the underlying ordinary shares on the date of grant. The grant date fair value of each equity instrument was US$145.21.

Activity in the RSUs, RSAs, and other contingently issuable shares outstanding and related information is as follows:

In the table above, the number of RSUs released include ordinary shares that the Group has withheld for settlement of employees’ tax obligations due upon the vesting of RSUs.

Activity in the stock options outstanding and related information is as follows:

The weighted-average contractual life for the stock options outstanding at December 31, 2019, 2018, and 2017 is 2.9 years, 2.9 years, and 3.3 years, respectively. The weighted-average share price at exercise for options exercised during 2019, 2018, and 2017 was US$141.82, US$152.33, and US$57.53, respectively. The weighted-average fair value of options granted during the year ended at December 31, 2019, 2018, and 2017 was US$34.63 per option, US$39.23 per option, and US$18.05 per option, and, respectively.

The stock options outstanding December 31, 2019, 2018, and 2017 are comprised of the following:

In determining the fair value of the employee share-based awards, the Group uses the Black-Scholes option-pricing model. The Company does not anticipate paying any cash dividends in the near future and therefore uses an expected dividend yield of zero in the option valuation model. The expected volatility is based on the historical volatility of public companies that are comparable to the Group over the expected term of the award. The risk-free rate is based on U.S. Treasury zero-coupon rates as the exercise price is based on a fixed USD amount. The expected life of the stock options is based on historical data and current expectations.

The following table lists the inputs to the Black-Scholes option-pricing models used for employee share-based payments for the years ended December 31, 2019, 2018, and 2017:

Valuation assumptions are determined at each grant date and, as a result, are likely to change for share-based awards granted in future periods. Changes to the input assumptions could materially affect the estimated fair value of share-based payment awards.

The sensitivity analysis below shows the impact of increasing and decreasing expected volatility by 10% as well as the impact of increasing and decreasing the expected life by one year. This analysis was performed on stock options granted in 2019. The following table shows the impact of these changes on stock option expense for the options granted in 2019:

The expense recognized in the consolidated statement of operations for employee share-based payments is as follows: