Share-based compensation
The following table shows the total share-based compensation expense recorded in the Consolidated Statements of Operations and Comprehensive Loss (in thousands):
202520242023
Research and development
$8,776 $7,771 $6,467 
Selling, general and administrative
$28,922 $26,419 $26,002 
Equity Incentive Plan
Under the Company’s Equity Incentive Plan ("EIP"), the Company may grant market value options, share appreciation rights or restricted shares, restricted share units ("RSUs"), performance share units and other share-based awards to the Company’s employees. The Company’s board members and consultants are eligible to receive awards under the Company’s non-employee sub-plan to the EIP. Awards may be granted at such times as the Company may determine, but will generally be granted annually following the end of the financial year. Awards vest at such times and as specified in the award agreement, typically being over a four-year period although the Company retains the discretion to provide for other vesting schedules. If the participant violates the non-competition, non-solicitation, confidentiality or other similar restrictive covenant provisions of any employment contract, the right of the participant to receive these shares on vesting shall terminate immediately. The Company maintains discretion over the type and terms of equity awards granted. Share options lapse on the tenth anniversary from the date of grant, and they are not subject to performance conditions or entitled to dividends. As of December 31, 2025, the Company has reserved 6,172,915 authorized shares for future issuance under the EIP.
During the years ended December 31, 2025 and 2024, options over a total of 1,793,514 shares and 1,062,745 shares respectively were awarded under the Company’s EIP. Of the above awards in the year ended December 31, 2025, there were 207,829 options awarded to the Company's non-executive directors, 183,386 of which vest on the first anniversary from the date of grant and 24,443 of which vest monthly over a three-year period. In fiscal year 2024, there were 85,595 non-executive options awarded, 72,670 of which vested on the first anniversary from the date of grant and 12,925 of which vest monthly over a three-year period.
Share option activity
The number and weighted average exercise prices of share options were as follows:
Number of shares issuable
Number of
Share Options
Weighted
Average
Exercise
Price
Weighted Average
Remaining
Contractual
Term
Aggregate
Intrinsic Value
(in thousands)
Outstanding as of December 31, 20249,422,875$31.14 6.0 years$50,455 
Awards granted1,793,51429.66 
Awards exercised(624,411)19.82 
Awards forfeited
(131,347)40.01 
Awards expired
(86,315)45.16 
Outstanding as of December 31, 202510,374,316$31.34 5.9 years$87,338 
Exercisable at December 31, 20257,857,031$28.59 5.0 years$77,958 
The weighted average fair value of options granted in 2025 was $16.05 (2024: $37.71; 2023: $38.57). The weighted average share price at the date of exercise of the options during the year was $33.47 (2024: $63.70; 2023: $56.73).
In the years ended December 31, 2025, 2024 and 2023, the total intrinsic value of stock options exercised was $8.8 million, $14.4 million and $58.4 million, respectively. The tax benefit arising on the exercise of stock options was $0.8 million, $2.2 million and $3.1 million for the years ended December 31, 2025, 2024 and 2023, respectively.
As of December 31, 2025, total unrecognized compensation expense related to share options granted but not vested was $18.7 million, which the Company expects to recognize over a remaining weighted-average period of 1.5 years.
Awards granted in the year ended December 31, 2025, 2024 and 2023, have been valued using the Black-Scholes option pricing model. The assumptions used in the models for share options granted during the years ended December 31, 2025, 2024 and 2023, were as follows:
202520242023
Share price at grant date
$28.63 - $35.93
$31.13 - $70.50
$46.48 - $64.53
Exercise price
$28.63 - $35.93
$31.13 - $70.50
$46.48 - $64.53
Expected volatility
52.11% - 55.78%
54.98% - 66.17%
66.70% - 72.05%
Expected life
5.5 years
5 years - 5.5 years
5 years
Risk free rate
3.73% - 4.41%
3.53% - 4.56%
3.52% - 4.75%
Fair value
$15.11 - $18.47
$16.53 - $40.47
$27.77 - $39.02
Restricted share unit activity
In February 2025, the Company granted RSU awards that vest over a four-year service period with 25% on each anniversary of the grant date. An RSU award represents the right to receive one of the Company’s ADSs upon vesting of the RSU. The fair value of each RSU award is based on the closing price of the Company’s ADSs on Nasdaq on the date of grant.
The number and weighted average fair value of RSUs were as follows:

Number of RSUsWeighted Average Grant Date Fair Value
Unvested and outstanding as of December 31, 2024$ 
Awards granted521,07229.87
Awards vested
Awards forfeited (24,916)29.70
Unvested and outstanding as of December 31, 2025
496,156$29.88 

As of December 31, 2025, total unrecognized compensation expense related to RSUs granted but not vested was $7.4 million, which the Company expects to recognize over a remaining weighted-average period of 2.1 years.

Historical Timeline

Fiscal YearFiled
2025Feb 25, 2026Showing above
2024Feb 26, 2025
2023Feb 28, 2024

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.