8. Common stock

12 Months Ended

Dec. 31, 2013

Notes to Financial Statements

Common stock - Note 8

8. Common stock

In September 2013, we raised $6.6 million before issuance costs of approximately $452,000 from the sale of 3.5 million shares of common stock and warrants to purchase up to an aggregate of 2.1 million shares of our common stock in a registered direct offering. Details of the warrants are described below in Note 9.

In May 2013, we raised $5.85 million before issuance costs of approximately $362,000 from the sale of 2.6 million shares of common stock and warrants to purchase up to an aggregate of 2.0 million shares of our common stock in a registered direct offering. Details of the warrants are described below in Note 9.

In June 2012, we raised $10.5 million before issuance costs of approximately $823,000 through an underwritten public offering of 4.2 million shares of our common stock and warrants to purchase 2.1 million shares of our common stock. Details of the warrants are described below in Note 9.

In May 2012, we raised approximately $5.0 million before issuance costs of approximately $71,000 from the sale of 3.3 million shares of common stock and warrants to purchase 1.0 million shares of our common stock to private investors. Details of the warrants are described below in Note 9.