NOTE 7. EQUITY INCENTIVE PLANS
Stock Option Plan
During the three and nine months ended September 30, 2020, options were granted to employees and members of the board of directors to purchase 460,167 and 3,109,683 shares, respectively, of the Company's common stock. The weighted-average grant-date estimated fair value of options granted during the three and nine months ended September 30, 2020 was $4.09 and $5.03, respectively.
During the three and nine months ended September 30, 2020, options were exercised to purchase 142,191 and 346,806 shares, respectively, of the Company's common stock, resulting in corresponding approximately $0.3 million and $0.8 million net proceeds, respectively, to the Company. During the three and nine months ended September 30, 2019, options were exercised to purchase 4,513 and 6,964 shares, respectively, of the Company's common stock, resulting in corresponding $13,000 and $21,000 net proceeds to the Company.
Restricted Stock Units (“RSUs”)
In July 2018, the Company granted 903,374 performance-based restricted stock units (“PRSUs”) to its employees that were to vest upon the achievement of certain performance conditions, subject to the employees’ continued service relationship with the Company through the achievement date. The primary performance condition was acceptance by the FDA of the Company’s filing of its New Drug Application (“NDA”) of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. Additionally, during the second quarter of 2020, the Company granted 30,000 PRSUs, in aggregate, with the same performance criteria to its chief commercial officer and chief financial officer hired during that period. On September 15, 2020, the Company announced the performance conditions were achieved and 866,528 of these PRSUs that were outstanding on the achievement date were vested and issued. Based on the achievement of the performance conditions, the Company recorded stock-based compensation expense of $0.2 million and $1.6 million for the three and nine months ended September 30, 2020, respectively. The Company had recorded a one-time catch-up of stock-based compensation expense of $2.1 million for each of the three and nine months ended September 30, 2019 as the related performance condition had become probable as of September 30, 2019. The related compensation cost was recognized as an expense ratably over the estimated vesting period. The expense recognized for these awards was based on the grant date fair value of the Company’s common stock multiplied by the number of units granted.
For each of the three and nine months ended September 30, 2020 and 2019, the Company issued 0 and 85,609 shares, respectively, of its common stock upon vesting of time-based RSUs to its employees. NaN time-based RSUs were granted to employees during the three and nine months ended September 30, 2020 or 2019.
Employee Stock Purchase Plan
In August 2020, the Company sold 94,127 shares of its common stock under the Company’s employee stock purchase program (“ESPP”). The shares were purchased by employees at a purchase price of $4.88 per share with proceeds to the Company of approximately $0.4 million. In February 2020, the Company sold 75,804 shares of its common stock under the ESPP. The shares were purchased by employees at a purchase price of $4.95 per share with proceeds to the Company of approximately $0.4 million.
In August 2019, the Company sold 77,698 shares of its common stock under the ESPP. The shares were purchased by employees at a purchase price of $2.58 per share with proceeds to the Company of approximately $0.2 million. In February 2019, the Company sold 83,046 shares of its common stock under the ESPP. The shares were purchased by employees at a purchase price of $2.39 per share with proceeds to the Company of approximately $0.2 million.
Issuance of Common Stock for Services
For the three and nine months ended September 30, 2020, the Company issued 0 and 42,403 shares, respectively, of its common stock to members of the board of directors who elected to receive stock in lieu of their cash fees under the Company’s Amended and Restated Non-Employee Director Compensation Program. The shares issued were valued at