Until the IPO in October 2015, the Company maintained and granted option awards under the 2003 Share Option Plan (the "2003 Plan") and the 2013 Equity Incentive Share Option Plan (the "2013 Plan") for the Company’s officers, directors, employees and advisors. The 2003 Plan and the 2013 Plan terminated as of the IPO as to future awards, but they continue to govern option awards previously granted thereunder.

In September 2015, the Company adopted the 2015 Omnibus Incentive Plan (the "2015 Plan"). The Company’s shareholders approved the 2015 Plan in September 2015. Under the 2015 Plan, the Company can issue various types of equity compensation awards such as restricted shares, performance shares, restricted stock units ("RSUs"), performance share units ("PSUs"), long-term cash award and other share-based awards. Options granted under the 2015 Plan generally have a vesting period of four years and expire ten years after the date of grant. RSUs granted under the 2015 Plan vest in equal installments over three years. PSUs granted under the 2015 Plan generally vest have a vesting period between three and six years, as performance targets are attained. Options, RSUs and PSUs granted under the 2015 Plan that are canceled before expiration become available for future grants.

On December 31, 2021, in accordance with the terms of the 2015 Plan, the number of shares available for issuance under the 2015 Plan automatically increased by 4% of the Company’s outstanding ordinary shares as of December 31, 2021. As a result, the number of shares available for issuance under the 2015 Plan increased from 35,107,569 shares to 39,264,853 shares. As of December 31, 2021,18,581,409 ordinary shares are available for grant under the 2015 Plan.

In September 2015, the Company adopted an ESPP to encourage and enable eligible employees to acquire ownership of the Company’s ordinary shares purchased through accumulated payroll deductions on an after-tax basis. The ESPP is intended to be an "employee stock purchase plan" within the meaning of Section 423 of the Code and the provisions of the ESPP will be construed in a manner consistent with the requirements of such

section. The Company began its offerings under the ESPP on August 1, 2016. The Company issued 51,370 ordinary shares for the plan period from January 1, 2021 through December 31, 2021.

The terms of the ESPP provide that on December 31 of each year, the number of shares available for purchase by eligible employees who participate in the ESPP automatically increases by 1% of the Company’s outstanding ordinary shares outstanding, unless the Company determines that such an increase is not necessary. The Company determined that an such increase was not necessary and no such increase took place. As of December 31, 2021, 4,954,997 ordinary shares are available for offering under the ESPP.

The fair value of share-based awards was estimated using the Black-Scholes model for all equity grants and for market condition awards. The Company also applied the Monte-Carlo simulation model, with the following underlying assumptions:


	Year ended December 31,
	2021		2020		2019
Stock Option Plans
Expected term (years)	5.50-6.00		5.50-6.00		5.50-6.00
Expected volatility	60%-63%		54%-56%		55%-61%
Risk-free interest rate	0.78%-1.27%		0.30%-0.86%		1.73%-2.40%
Dividend yield	0.00	%	0.00	%	0.00	%
ESPP
Expected term (years)	0.50		0.50		0.50
Expected volatility	54%-81%		47%-66%		44%-62%
Risk-free interest rate	0.05%-0.09%		0.17%-1.57%		2.10%-2.51%
Dividend yield	0.00	%	0.00	%	0.00	%


	Year ended December 31, 2021
	Number of options	Weighted average exercise price		Aggregate intrinsic value
Outstanding at beginning of year	9,220,326	$	26.21
Granted	466,360	149.96
Exercised	(1,016,369)	20.81
Forfeited and cancelled	(120,995)	62.77
Outstanding at end of year	8,549,322	$	33.09	$	394,997
Exercisable options	5,145,149	$	19.76	$	285,295


	Year ended December 31, 2021
	Number of RSUs/PSUs	Weighted average grant date fair value price		Aggregate intrinsic value
Unvested at beginning of year	4,466,151	$	54.06
Granted	632,275	138.37
Vested	(569,248)	52.63
Forfeited and cancelled	(70,071)	94.41
Unvested at end of year (1)	4,459,107	$	65.56	$	334,790

(1) Includes PSUs that have a mix of service, market and other milestone performance vesting conditions which are vested upon achievements of market and performance conditions which are not probable, as of December 31, 2021, in accordance with ASC 718 as follows:


December 31, 2021
Number of PSUs	Fair value at grant date per PSU		Total fair value at grant date
2,703,852	$	48.16	$	130,218
108,113	69.37		7,500
17,712	84.68		1,500
10,532	94.94		1,000
189,626	$	114.26	$	21,667
3,029,835			$	161,885

The total equity-based compensation expense related to all of the Company’s equity incentive plans recognized for the years ended December 31, 2021, 2020 and 2019, was comprised as follows:


	Year ended December 31,
	2021		2020		2019
Cost of revenues	$	3,471	$	2,221	$	2,231
Research, development and clinical studies	27,597		18,125		7,570
Sales and marketing	22,673		17,672		11,897
General and administrative	41,159		37,703		30,718
Total share-based compensation expense	$	94,900	$	75,721	$	52,416

As of December 31, 2021, unamortized share-based compensation costs amounted to $96,379 and are expected to be recognized over a weighted average period of approximately 2.63 years.

The weighted average grant date exercise price of the Company’s options granted during the years ended December 31, 2021, 2020 and 2019 were $149.96, $71.87 and $50.45 per share, respectively.

The weighted average grant date fair values of the Company’s options forfeited and cancelled during the years ended December 31, 2021, 2020 and 2019 were $62.77, $22.98 and $22.11, respectively.

The aggregate intrinsic values for the options exercised during the years ended December 31, 2021, 2020 and 2019 were $143,695, $156,910 and $266,626, respectively. The aggregate intrinsic value is calculated as the difference between the per share exercise price and the deemed fair value of the Company’s ordinary shares for each share subject to an option multiplied by the number of shares subject to options at the date of exercise. The Company


Exercise price	Number of options outstanding	Weighted average remaining contractual term	Number of options exercisable	Weighted average remaining contractual term
$		(years)		(years)
0.00 - 10.00	1,116,075	4.48	1,116,075	4.48
10.01 - 20.00	2,668,814	4.94	1,787,295	4.74
20.01 - 30.00	1,886,852	5.53	1,461,424	5.35
30.01 - 40.00	331,417	6.56	272,217	6.54
40.01 - 60.00	1,200,783	7.29	274,740	7.21
60.01 - 100.00	871,555	8.18	227,804	8.13
100.01 - 160.00	462,606	9.25	5,594	8.85
160.01 - 220.00	11,220	9.42	—	0.00
	8,549,322	5.97	5,145,149	5.24