Under authoritative guidance used by the FASB on determining whether an instrument (or embedded feature) is indexed to an entity’s own stock, instruments that do not have fixed settlement provisions are deemed to be derivative instruments. The Company has issued certain convertible notes whose conversion prices contains reset provisions based on a future offering price and/or whose conversion prices are based on future market prices. However, since the number of shares to be issued is not explicitly limited, the Company is unable to conclude that enough authorized and unissued shares are available to share settle the conversion option. In addition, the Company also granted certain warrants that included a fundamental transaction provision that could give rise to an obligation to pay cash to the warrant holder.

As a result, the conversion option and warrants are classified as liabilities and are bifurcated from the debt host and accounted for as a derivative liability in accordance with ASC 815 and will be re-measured at the end of every reporting period with the change in value reported in the statement of operations.

The derivative liabilities were valued using a probability weighted average Black-Scholes-Merton pricing model with the following average assumptions:

The expected life of the conversion feature of the notes and warrants was based on the remaining contractual term of the notes and warrants. The Company uses the historical volatility of its Common Stock to estimate the future volatility for its Common Stock. The expected dividend yield was based on the fact that the Company has not paid dividends in the past and does not expect to pay dividends in the future. The risk-free interest rate was based on rates established by the Federal Reserve Bank. As of December 31, 2018, the Company had recorded a derivative liability of $2,576,000.

During the six months ended June 30, 2019, the Company recorded an additional derivative liability totaling $388,000 as a result of the issuance of a convertible note. The Company also recorded a change in fair value of $518,000 to account the changes in fair value of these derivative liabilities for the six months ended June 30, 2019. In addition, the Company also recorded a gain on extinguishment of $2,227,000 to account for the extinguishment of derivative liabilities associated with the payoff of convertible debt for the six months ended June 30, 2019. At June 30, 2019, the fair value of the derivative liability amounted to $219,000. The details of derivative liability transactions for the six months ended June 30, 2019 and 2018 are as follows: