10. Share-Based Compensation

On November 18, 2015, the Company’s Board of Directors adopted and approved the 2015 Equity Incentive Plan (the “2015 Plan”), which authorized the Company to grant up to 223,424 ordinary shares in the form of incentive share options, nonstatutory share options, share appreciation rights, restricted share awards, restricted share units and other share awards. The types of share-based awards, including the rights amount, terms, and exercisability provisions of grants are determined by the Company’s Board of Directors. The purpose of the 2015 Plan is to provide the Company with the flexibility to issue share-based awards as part of an overall compensation package to attract and retain qualified personnel. On May 18, 2017, the Company amended the 2015 Plan to increase the number of ordinary shares available for issuance under the 2015 Plan by 219,605 shares to 443,029 shares.

On March 14, 2018, the Company’s Board of Directors adopted and approved the 2018 Equity Incentive Plan (the “2018 Plan”), which became effective upon the execution and delivery of the underwriting agreement related to our IPO in May 2018. No further grants will be made under the 2015 Plan. The ordinary shares underlying any options that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2015 Plan will not be added back to the ordinary shares available for issuance.

The 2018 Plan, adopted and approved on March 14, 2018, authorized the Company to grant up to 1,018,459 ordinary shares in the form of incentive share options, nonstatutory share options, share appreciation rights, restricted share awards, restricted share units, performance share awards, performance cash awards and other share awards. The types of share-based awards, including the amount, terms, and exercisability provisions of grants are determined by the Company’s Board of Directors. The ordinary shares underlying any options that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2018 Plan will be added back to the ordinary shares available for issuance under the 2018 Plan.

On December 5, 2018, pursuant to powers delegated to it by the Board of Directors of the Company, the Compensation Committee approved an increase in the number of ordinary shares available to be granted pursuant to the 2018 plan by 4% of the total number of shares of the Company’s issued share capital on December 31, 2018, being 574,081 ordinary shares.

Restricted Ordinary Shares

In connection with the Company’s formation, 413,110 restricted ordinary shares were issued on October 14, 2015 to the Company’s founders at par value. These ordinary shares are subject to various restrictions pursuant to ordinary share purchase agreements between the Company and each founder, including restrictions on transfer and a Company right of repurchase. The restricted ordinary shares were 25% vested as of October 14, 2016 and 1/36th of the remaining restricted ordinary shares vest on a monthly basis thereafter (subject to acceleration of vesting in connection with certain change of control transactions). A change in status occurred on November 18, 2015 when the founders became employees of the Company. The grant date of these shares is now considered to be November 18, 2015 when the fair value was $3.14 per share.

The Company records share-based compensation expense for the restricted ordinary shares based on the grant date fair value. The Company recorded an expense of $85 and $82 for the three months ended March 31, 2019 and 2018, respectively. Total unamortized compensation expense related to restricted ordinary shares was $175 and $510 as of March 31, 2019 and March 31, 2018, respectively, expected to be recognized over a weighted average period of 0.54 years and 1.54 years as of March 31, 2019 and March 31, 2018, respectively.

The following table summarizes restricted ordinary shares activity for the three months ended March 31, 2019:

Share Options

The Company granted 442,500 share options to employees and directors during the three months ended March 31, 2019. The Company awarded 74,152 share options to employees during the three months ended March 31, 2018 under the 2018 Plan. These options were granted and priced upon execution of the underwriting agreement related to the IPO in May 2018. There were 984,913 and 221,553 unvested employee options outstanding as of March 31, 2019 and March 31, 2018, respectively. Total expense recognized related to the employee share options was $307 and $67 for the three months ended March 31, 2019 and 2018, respectively. Total unamortized compensation expense related to employee share options was $4,168 and $1,132 as of March 31, 2019 and March 31, 2018, respectively, which is expected to be recognized over a remaining average vesting period of 3.30 years and 3.27 years as of March 31, 2019 and March 31, 2018, respectively.

The assumptions that the Company used to determine the grant date fair value of employee and director options granted were as follows, presented on a weighted average basis:

The following table summarizes the number of options outstanding and the weighted-average exercise price:

Restricted share units (RSUs)

No RSUs were awarded to directors during the three months ended March 31, 2019. No RSUs were awarded or outstanding during the three months ended March 31, 2018.

The table below shows the number of RSUs granted covering an equal number of our ordinary shares and the weighted-average grant date fair value of the RSUs granted:

The fair value of RSUs is determined on the date of grant based on the market price of our ordinary shares on that date. The fair value of RSUs is expensed ratably over the vesting period, which is generally one year for directors. Total expense recognized related to the RSUs was $119 for the three months ended March 31, 2019. Total unamortized compensation expense related to RSUs was $72 as of March 31, 2019, which is expected to be recognized over a remaining average vesting period of 0.15 years as of March 31, 2019.

The Company awarded 50,000 RSUs to certain employees during the three months ended March 31, 2019 which are subject to certain performance based vesting conditions (Performance RSUs). No Performance RSUs were awarded or outstanding during the three months ended March 31, 2018.

The table below shows the number of Performance RSUs granted covering an equal number of our ordinary shares and the weighted-average grant date fair value of the Performance RSUs granted:

The weighted average grant date fair value of restricted share units with a market condition was determined using the Monte Carlo simulation model. The fair value of Performance RSUs is expensed ratably over the vesting period. Total expense recognized related to the Performance RSUs was $29 for the three months ended March 31, 2019. Total unamortized compensation expense related to Performance RSUs was $381 as of March 31, 2019, which is expected to be recognized over approximately the next 1.56 years as of March 31, 2019.

The Company’s share-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows:

There was a total of $4,796 and $1,642 unamortized share-based compensation expense for restricted ordinary shares, options, restricted share units and performance restricted share units as of March 31, 2019 and March 31, 2018, respectively, which is expected to be recognized over a remaining average vesting period of 2.98 years and 2.32 years as of March 31, 2019 and March 31, 2018, respectively.