Agreements with Teva Pharmaceuticals-

On September 13, 2011, the Company signed a Share Purchase Agreement with Teva Pharmaceuticals Industries Limited (“Teva”). Under the terms of this agreement, Teva purchased at an initial closing 687,442 shares of the Company’s common stock for $7.5 million and, concurrent with the purchase of the common stock, obtained options to purchase up to an additional $37.5 million of the Company’s common stock. Teva never exercised any options to purchase additional common stock, and all options have expired as of December 31, 2014.

Contemporaneously with the signing of the Share Purchase Agreement, the Company also signed a Research and Collaboration Agreement and an Exclusive License Option Agreement with Teva. Under the terms of the Research and Collaboration Agreement, the Company carried out a research and development program (“R&D Program”) to develop novel therapeutics for Hepatitis C that target the viral polymerase enzyme involved in replication of the virus. The R&D Program has been concluded. Teva's options to extend the R&D Program or to receive a license to the technology developed by the Company under the R&D Program have expired. The Company retains all rights to the technology.

Accounting Treatment

The Company determined that Teva’s options to purchase additional shares of common stock were freestanding instruments that were required to be classified as liabilities and carried at fair value under the provisions of ASC 480-10, Distinguishing Liabilities from Equity. Accordingly, the Company allocated the proceeds from the initial $7.5 million investment between the common stock and the options to purchase additional shares of common stock under the terms outlined in the Share Purchase Agreement. The Company recorded a liability of $4.2 million for the initial fair value of Teva’s options in 2011, and allocated the remainder of the proceeds to common stock issued for $3.1 million, net of transaction costs of $172,000.

The liability representing the fair value of the options was included on the accompanying balance sheets as “Derivative liability” and was required to be remeasured at fair value at each reporting date. The fair value of the options to purchase additional common stock was estimated using a probability-weighted Black-Scholes-Merton model. As of December 31, 2013, the fair value of the liability was approximately $23,000, which represented a reduction in fair value during the year ended December 31, 2013 of approximately $192,000.  As of December 31, 2014, all such options had expired and the liability had been reduced to zero.