Stockholders' Equity	12 Months Ended
Dec. 31, 2020
Federal Home Loan Banks [Abstract]
Stockholders' Equity	4. STOCKHOLDERS’ EQUITY Preferred Stock Preferred stock of 50.0 million shares, with a $0.0001 par value, is authorized but unissued. Follow-on Public Offerings On May 22, 2018, we completed a follow-on offering of our common stock. We sold an aggregate of 4,057,500 shares of common stock at a price of $15.00 per share, including 457,500 shares of common stock pursuant to the exercise of the underwriters’ option to purchase additional shares. In the aggregate, we received net proceeds from the follow-on offering and exercise of the overallotment option of $57.0 million, after deducting underwriting discounts and commissions of $3.2 million and offering expenses totaling $0.7 million. As part of the follow-on offering, Cellectis purchased 550,000 shares of common stock for a value of $8.3 million, the proceeds of which are included in the net proceeds of $57.0 million. On October 20, 2020, we completed a follow-on offering of our common stock. We sold an aggregate of 3,750,000 shares of common stock at a price of $4.00 per share. In the aggregate, we received net proceeds from the follow-on offering of $14.0 million, after deducting $1.0 million of placement and agent fees and other offering expenses. As part of the follow-on offering, Cellectis purchased 1,250,000 shares of common stock for a value of $5.0 million, the proceeds of which are included in the net proceeds of $14.0 million. Share Repurchases We repurchased $0.8 million of common stock in 2019 and $0.2 million in 2018.

Stockholders' Equity

12 Months Ended

Dec. 31, 2020

4. STOCKHOLDERS’ EQUITY

Preferred Stock

Preferred stock of 50.0 million shares, with a $0.0001 par value, is authorized but unissued.

Follow-on Public Offerings

On May 22, 2018, we completed a follow-on offering of our common stock. We sold an aggregate of 4,057,500 shares of common stock at a price of $15.00 per share, including 457,500 shares of common stock pursuant to the exercise of the underwriters’ option to purchase additional shares. In the aggregate, we received net proceeds from the follow-on offering and exercise of the overallotment option of $57.0 million, after deducting underwriting discounts and commissions of $3.2 million and offering expenses totaling $0.7 million. As part of the follow-on offering, Cellectis purchased 550,000 shares of common stock for a value of $8.3 million, the proceeds of which are included in the net proceeds of $57.0 million.

On October 20, 2020, we completed a follow-on offering of our common stock. We sold an aggregate of 3,750,000 shares of common stock at a price of $4.00 per share. In the aggregate, we received net proceeds from the follow-on offering of $14.0 million, after

deducting $1.0 million of placement and agent fees and other offering expenses. As part of the follow-on offering, Cellectis purchased 1,250,000 shares of common stock for a value of $5.0 million, the proceeds of which are included in the net proceeds of $14.0 million.

Share Repurchases

We repurchased $0.8 million of common stock in 2019 and $0.2 million in 2018.