Stockholders' Equity

3 Months Ended

Mar. 31, 2013

Stockholders' Equity

Stockholders' Equity

(10) Stockholders’ Equity

In January 2011, the Company entered into a controlled equity offering sales agreement (the “Cantor Agreement”) with Cantor Fitzgerald & Co. pursuant to which the Company could issue and sell up to 5,000,000 shares of its common stock from time to time through Cantor, acting as agent.  During the three months ended March 31, 2012, the Company issued 2,450,000 shares of common stock under the Cantor Agreement and raised $8.5 million in net proceeds.

In September 2012, the Company and Cantor amended the Cantor Agreement (the “Cantor Amendment”) to allow the Company to issue and sell additional shares of its common stock having an aggregate offering price of up to $44.0 million. Under the Cantor Amendment, the Company will pay Cantor a fixed commission rate of 3.0% of the gross sales price per share of any common stock sold through Cantor. The Cantor Amendment terminates upon ten day notice by either Cantor or the Company.  During the three months ended March 31, 2013, the Company issued 2,433,608 shares under the Cantor Amendment and raised $17.1 million in net proceeds. At March 31, 2013, the Company had $4.4 million remaining in aggregate offering price available under the Cantor Amendment which may be sold upon the expiration of the 90-day lock-up with the underwriters of the Company’s underwritten public offering in February 2013.

During the three months ended March 31, 2012, the Company issued 12,075,000 shares of its common stock in an underwritten public offering, including the underwriter’s exercise of their full over-allotment option to purchase an additional 1,575,000 shares of common stock. The net proceeds to the Company were $43.4 million, after deducting underwriting fees and offering expenses.

During the three months ended March 31, 2013, the Company issued 13,800,000 shares of its common stock in an underwritten public offering, including the underwriter’s exercise of their full over-allotment option to purchase an additional 1,800,000 shares of common stock. The net proceeds to the Company were $97.0 million, after deducting underwriting fees and offering expenses.