We have 10.0 million shares of preferred stock authorized for issuance, par value of $0.001 per share. As of December 31, 2020 and 2019, no shares of preferred stock were issued and outstanding.

On May 21, 2019, our stockholders approved and we filed an amendment to our Fifth Amended and Restated Certificate of Incorporation, as amended, to increase the total number of authorized shares of common stock from 50.0 million to 100.0 million. Each holder of our common stock, par value of $0.001 per share, is entitled to one vote for each share of such stock held. As of December 31, 2020 and 2019, there were 55.7 million and 45.3 million shares of common stock issued and outstanding.

The following table presents common stock reserved for future issuance for the following financial instruments:


	December 31,
(In thousands)	2020	2019
Stock options and RSUs outstanding	5,703	4,692
Warrants to purchase common stock	28	28
Reserved for future grants under employee equity plans	3,899	4,926
Reserved for issuance upon conversion of Convertible Senior Notes	12,313	—
Total	21,943	9,646

At December 31, 2020, we had approximately 22.3 million shares of authorized and unreserved common stock available for issuance.

We have an at-the-market sales agreement (the ATM Sales Agreement) with Cantor Fitzgerald & Co. (Cantor) pursuant to which Cantor agreed to act as a sales agent in connection with sales of our common stock from time to time pursuant to an effective registration statement.

In December 2017, we filed a prospectus supplement to our automatic “shelf” registration statement on Form S-3 registering the offering, issuance and sale of up to $75.0 million in gross aggregate proceeds of common stock under the ATM Sales Agreement. During 2019 and 2018, we sold approximately 0.9 million and 0.7 million shares of common stock, respectively, resulting in net proceeds of approximately $42.6 million and $30.3 million, respectively, after deducting commissions and other offering costs.

In June 2020, we filed a prospectus supplement to our automatic “shelf” registration statement on Form S-3 registering the offering, issuance and sale of up to $200.0 million in gross aggregate proceeds of our common stock under the ATM Sales Agreement. During 2020, we sold approximately 0.2 million shares of common stock and realized net proceeds of approximately $4.9 million, after deducting commissions and other offering costs.

In August 2018, we completed an underwritten public offering of 6.0 million shares of our common stock at an offering price of $52.00 per share. Net proceeds realized from the offering amounted to approximately $292.9 million, after deducting commissions and other offering expenses.

In March 2020, we completed an underwritten public offering of 9.8 million shares of our common stock at an offering price of $23.50 per share, including 1.3 million shares sold pursuant to the underwriters’ full exercise of their option to purchase additional shares. Net proceeds realized from the offering amounted to approximately $221.7 million, after deducting commissions and other offering costs.

A summary of changes in the balances of each component of accumulated other comprehensive loss, net of tax, follows:


(In thousands)	Net Unrealized Gains (Losses) on Marketable Securities		Foreign Currency Translation Adjustments		Accumulated Other Comprehensive Income
Balance at December 31, 2017	$	—	$	—	$	—
Amounts arising during the period	3		—		3
Balance at December 31, 2018	3		—		3
Amounts arising during the period	702		—		702
Reclassification adjustments	(326)		—		(326)
Balance at December 31, 2019	379		—		379
Amounts arising during the period	(197)		(260)		(457)
Reclassification adjustments	7		—		7
Balance at December 31, 2020	$	189	$	(260)	$	(71)