Under the Company's stock option plan, options, rights and other entitlements be granted to directors, officers, employees and consultants of the Company to purchase up to a maximum of of the total number of outstanding common shares, estimated at million options, rights and other entitlements as at Options are granted at the fair market value of the common shares on the closing trading price of the Company's stock on the day prior to the grant if the grant is made during the trading day or the closing trading price on the day of grant if the grant is issued after markets have closed. Options vest at various rates (immediate to years) and have a term of years.

Stock option transactions for the years ended and are summarized as follows:

 

Option numbers are in (000's)
										Weighted average				Aggregate
		Options				Weighted average exercise price				remaining contractual life (years)				Intrinsic Value
Outstanding, December 31, 2018			4,489				3.11
Granted			2,160				2.00
Exercised			(312	)			2.32
Expired			(67	)			4.61
Forfeited			(329	)			2.36
Outstanding, December 31, 2019			5,941			$	2.84
Granted			6,362				6.81
Exercised			(235	)			2.45
Forfeited			(126	)			4.50
Outstanding, December 31, 2020			11,942				4.97				7.9			$	9,142,263
Exercisable, December 31, 2020			4,363				3.06				6.2			$	6,470,708
Vested and expected to vest, December 31, 2020			10,804				4.86				7.8			$	8,741,530

 

Aggregate intrinsic value represents the excess of the value of the closing stock price on the previous trading day of the respective balance sheet dates over the exercise price of the stock options. Total intrinsic value of options exercised was thousand for ( – thousand).

 

As of there was million of total unrecognized compensation cost related to non-vested stock options, which is expected to be recognized over an estimated weighted-average period of years.

 

The following table presents the weighted average assumptions that were used in the Black-Scholes option pricing model to determine the fair value of stock options granted during the year, and the resultant weighted average fair values:

 

			Year ended December 31, 2020				Year ended December 31, 2019
Risk-free interest rate			1.27	%			2.18	%
Expected dividend yield			-				-
Expected volatility			85.9	%			83.9	%
Expected life of options (years)			5				5
Grant date fair value		$	4.59			$	1.34

 

The Company uses historical data to estimate the expected dividend yield and expected volatility of its common shares in determining the fair value of stock options. The expected life of the options represents the estimated length of time the options are expected to remain outstanding.

 

The following table presents the vesting terms of options granted in the period:

 

Option numbers are in (000's)			Year ended December 31, 2020				Year ended December 31, 2019
			Number of options				Number of options
Cliff vesting after one year anniversary			300				335
3 year vesting (50%-25%-25%)			862				160
4 year vesting (50%-16 2/3%-16 2/3%-16 2/3%)			5,200				1,665
Total stock options granted in the period			6,362				2,160

 

The Company has a stock incentive plan (SIP) pursuant to which the Board grant stock-based awards comprised of restricted stock units or dividend equivalents to employees, officers, consultants, independent contractors, advisors and non-employee directors of the Company. Each restricted unit is automatically redeemed for common share of the Company upon vesting. The following table presents the activity under the SIP plan for the year ended and the units outstanding.

 

		Year ended, December 31, 2020								Year ended, December 31, 2019
			Number (in thousands)				Weighted average grant date fair value				Number (in thousands)				Weighted average grant date fair value
Outstanding, beginning of year			40			$	2.00				-			$	-
Granted			645				7.32				80				2.00
Redeemed			(685	)			7.01				(40	)			2.00
Outstanding, end of year			-			$	-				40			$	2.00

 

On the Company granted restricted share units (RSUs) with a vesting term of months. On the vesting term on the RSUs was extended from months to months. On all of these restricted share units were vested and were redeemed for common shares.

 

On the Company granted restricted share units (RSUs), restricted share units of which have a vesting term of months and the balance having a vesting term of year. On of these restricted share units were vested and were redeemed for common shares. On the vesting term on the balance was extended from year to year and month. On the remaining of these restricted share units were vested and were redeemed for common shares.

 

The grant date fair value of the and RSUs were determined as the closing value of the common shares of the Company on the Nasdaq Stock Market on the date prior to the date of grant.

 

The Company recorded share-based payment expense related to stock options and RSUs as follows:

 

			Year ended December 31, 2020				Year ended December 31, 2019
Research and development		$	3,720			$	474
General and administrative			17,718				1,822
Total		$	21,438			$	2,296