Sale of Additional Common Stock	12 Months Ended
Dec. 31, 2018
Sale of Additional Common Stock
Sale of Additional Common Stock	4. Sale of Additional Common Stock In March 2015, we completed the sale of 8,625,000 shares of common stock which included shares we issued pursuant to our underwriters’ exercise of their over-allotment option pursuant to a follow-on offering. We received net proceeds of $115.2 million, after underwriting discounts, commissions and estimated offering expenses. In December 2016, we completed the sale of 5,272,750 shares of common stock which included shares we issued pursuant to our underwriters’ exercise of their over-allotment option pursuant to a follow-on financing. We received net proceeds of $119.3 million after underwriting discounts, commissions and offering expenses. In March 2018, we completed the sale of 8,395,000 shares of commons stock which included shares we issued pursuant to our underwriters’ exercise of their over-allotment option pursuant to a follow-on financing. We received net proceeds of $245.5 million, after underwriters discounts and offering expenses. On September 19, 2016, we entered into an Equity Distribution Agreement (the Distribution Agreement) with Piper Jaffray & Co (Piper Jaffray) pursuant to which we may sell from time to time, at our option, up to an aggregate of $40 million of common stock through Piper Jaffray as sales agent. The issuance and sale of these shares by Xencor under the Distribution Agreement will be pursuant to our shelf registration statement on Form S-3 (File No.333-213700) declared effective by the SEC on October 5, 2016. We are not obligated sell any shares of common stock under the Distribution Agreement, and to date we have not sold any shares under the Distribution Agreement.

4. Sale of Additional Common Stock

In March 2015, we completed the sale of 8,625,000 shares of common stock which included shares we issued pursuant to our underwriters’ exercise of their over-allotment option pursuant to a follow-on offering. We received net proceeds of $115.2 million, after underwriting discounts, commissions and estimated offering expenses.

In December 2016, we completed the sale of 5,272,750 shares of common stock which included shares we issued pursuant to our underwriters’ exercise of their over-allotment option pursuant to a follow-on financing. We received net proceeds of $119.3 million after underwriting discounts, commissions and offering expenses.

In March 2018, we completed the sale of 8,395,000 shares of commons stock which included shares we issued pursuant to our underwriters’ exercise of their over-allotment option pursuant to a follow-on financing. We received net proceeds of $245.5 million, after underwriters discounts and offering expenses.

On September 19, 2016, we entered into an Equity Distribution Agreement (the Distribution Agreement) with Piper Jaffray & Co (Piper Jaffray) pursuant to which we may sell from time to time, at our option, up to an aggregate of $40 million of common stock through Piper Jaffray as sales agent. The issuance and sale of these shares by Xencor under the Distribution Agreement will be pursuant to our shelf registration statement on Form S-3 (File No.333-213700) declared effective by the SEC on October 5, 2016. We are not obligated sell any shares of common stock under the Distribution Agreement, and to date we have not sold any shares under the Distribution Agreement.