During 2013, the Company adopted an equity compensation plan, the 2013 Equity Incentive Plan, or 2013 Plan, for eligible employees, officers, directors, advisors, and consultants. The 2013 Plan provided for the grant of incentive and non-statutory stock options. In June 2018, the Company's board of directors and stockholders approved the 2018 Equity Incentive Plan, or 2018 Plan. Any shares of common stock covered by awards granted under the 2013 Plan that terminated after June 22, 2018 by expiration, forfeiture, or cancellation were added to the 2018 Plan reserve and shares available for future issuance under the 2013 Plan were canceled.

The initial number of shares of common stock available for issuance under the 2018 Plan was 4,000,000. Unless our board of directors provides otherwise, beginning on January 1, 2019 and continuing until the expiration of the 2018 Plan, the total number of shares of common stock available for issuance under the 2018 Plan will automatically increase annually on January 1 by the lesser of (i) 3,200,000 shares of Common Stock, (ii) 4% of the total number of issued and outstanding shares of common stock as of December 31 of the immediately preceding year and (iii) an amount determined by the board of directors. Under the 2018 Plan, any shares that are forfeited or expired are added back to the shares available for issuance. In the year ended December 31, 2019, the number of shares of common stock reserved for issuance under the 2018 Plan was increased by 1,685,929 shares. As of December 31, 2019, 2,098,380 shares of common stock were available for future issuance of options and restricted stock and other stock-based awards under the 2018 Plan.

The terms of the stock option agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the plans. Options granted by the Company vest over a period of one to four years and are exercisable after they have been granted for up to 10 years from the date of grant. Per the Company’s equity incentive plan, the term of the option expires, upon the earliest of 1) termination of continuous service for cause 2) three months after the termination of continuous service for reasons other than cause, death or disability 3) 12 months after the termination of continuous service due to disability 4) 18 months after the employee’s death if the employee died during the period of continuous service 5) expiration date in the grant notice or 6) the day before the tenth anniversary of the date of grant. The exercise price of the incentive stock options must equal at least the fair market value of the stock on the date of grant.

The 2013 Plan and the 2018 Plan allow for early exercise where the option holders may exercise their options prior to vesting. Common stock that is issued upon the early exercise of options is subject to repurchase by the Company at the original exercise price at the option of the Company. As of December 31, 2019 and 2018, there were 5,040 shares and 20,193 shares, respectively, of common stock that were subject to repurchase with an aggregate purchase price of approximately $17 thousand and $89 thousand reflecting a weighted average price of $3.47 and $4.40 per share, respectively.


	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (thousands)




Balance at December 31, 2018	4,577,515	$	5.99	8.0	$	84,290
Granted	3,720,091	29.71
Exercised	(1,108,700)	1.77
Forfeited or canceled	(390,923)	28.29
Balance at December 31, 2019	6,797,983	$	18.38	8.4	$	133,892
Vested and expected to vest at December 31, 2019	6,471,442	$	17.96	8.3	$	129,998

Beginning in the year ended December 31, 2018, the Company began to issue restricted stock units, or RSUs, to directors under the 2018 Plan. Awards granted to directors vest on the earlier of the one-year anniversary of the award's date of grant or the date of the Company’s next annual meeting of stockholders that occurs following the date of grant.

In June 2018, the Company's board of directors and stockholders approved the Tricida Inc. ESPP, or ESPP. The ESPP allows eligible employees to have up to 15.0% of their eligible compensation withheld and used to purchase common stock, subject to a maximum of $25,000 worth of stock purchased in a calendar year or no more than 2,500 shares in an offering period, whichever is less. An offering period consists of a six-month purchase period, with a look back feature to our stock price at the commencement of the offering period. Eligible employees can purchase the Company’s common stock at the end of the offering period at 85.0% of the lower of the closing price of our common stock on The Nasdaq Global Select Market on the first and last day of the offering periods.

The initial number of shares of common stock available for issuance under the ESPP, was 800,000. Unless the Company's board of directors provides otherwise, beginning on January 1, 2019, the maximum number of shares which shall be made available for sale under the ESPP will automatically increase on the first trading day in January of each calendar year during the term of the ESPP by an amount equal to the lesser of (i) one percent (1.0%) of the total number of shares issued and outstanding on December 31 of the immediately preceding calendar year, (ii) 800,000 shares or (iii) an amount determined by the board of directors.

In the year ended December 31, 2019, the number of shares of common stock reserved for issuance under the ESPP was increased by 421,482 shares. The Company issued 44,437 shares under the ESPP, representing approximately $1.1 million in employee contributions, for the year ended December 31, 2019. As of December 31, 2019, there were 1,158,936 shares of commons stock were available for future issuance under the ESPP.

In August 2019, the Company granted 594,000 stock options under its 2018 Plan with a performance based milestone with graded vesting over 18 months. Compensation expense for the performance-based awards is recorded over the estimated service period when the performance conditions are deemed probable of achievement. For the year ended December 31, 2019, the stock compensation expense recorded during the period was for service-based awards and performance conditions deemed probable of achievement and/or achieved.

As stock-based compensation recognized is based on options ultimately expected to vest, the expense has been reduced for estimated forfeitures. The Company uses the Black-Scholes option pricing model to determine the estimated fair value of stock options at the date of the grant. The Black-Scholes model includes inputs that require the input of subjective assumptions, including expected volatility, expected dividend yield, expected term, risk-free rate of return, and the estimated fair value of the underlying common stock on the date of grant.

Expected Term: The expected term of the options represents the average period the stock options are expected to remain outstanding. As the Company does not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior, the expected term of options granted is derived from the average midpoint between the weighted average vesting term and the contractual term, also known as the simplified method.

Expected Volatility: Beginning in the fourth fiscal quarter of 2019, expected volatility is estimated using a weighted-average historical volatility for our common stock and the historical volatility of the common stock of a representative group of comparable publicly traded companies over a period equal to the expected term of the stock option grants. Prior to the fourth fiscal quarter of 2019, since the Company did not have sufficient trading history for its common stock, the expected volatility was based on the historical volatility of the common stock of comparable publicly traded companies. The Company selected companies with comparable characteristics, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the Company's stock-based awards.


	Years Ended December 31,
	2019		2018		2017
Risk-free interest rate	2.5	%	2.7	%	1.7% - 2.2%
Expected volatility	76.4	%	68.4	%	70.8% - 73.1%
Expected term (in years)	6.4		10.0		6.5 - 8.9
Expected dividends	—	%	—	%	—	%


	Years Ended December 31,
(in thousands, except per share amounts)	2019		2018		2017
Stock options granted - weighted-average grant date fair value per share	$	19.28	$	10.39	$	1.67

Stock options exercised - intrinsic value	34,416		1,935		30

As of December 31, 2019, there was approximately $54.6 million of unrecognized stock-based compensation associated with stock options which the Company expects to recognize over a weighted-average period of 2.6 years. As of December 31, 2019, there was approximately $0.2 million of unrecognized stock-based compensation associated with RSUs which the Company expects to recognize over a weighted-average period of 0.4 years.