12.Severance Agreement with Former Chief Executive Officer

In December 2014, we entered into a severance agreement with our former Chief Executive Officer (CEO) pursuant to his resignation as CEO and member of the Board of Directors effective November 20, 2014, and his retirement effective December 31, 2014. The severance agreement provided for, among other benefits, cash severance payments of $1.1 million payable in installments over a duration of 18 months beginning on January 1, 2015, which is included as part of the Accrued Compensation account in the Balance Sheets. The change in the severance liability to our former CEO for the three months ended March 31, 2015 was as follows (in thousands):