The Company held certain assets and liabilities that are required to be measured at fair value on a recurring basis. These assets and liabilities include cash and cash equivalents, restricted cash, contingent consideration and warrant liabilities. ASC 820-10 (“Fair Value Measurement Disclosure”) requires the valuation using a three-tiered approach, which requires that fair value measurements be classified and disclosed in one of three tiers. These tiers are: Level 1, defined as quoted prices in active markets for identical assets or liabilities; Level 2, defined as valuations based on observable inputs other than those included in Level 1, such as quoted prices for similar assets and liabilities in active markets, or other inputs that are observable or can be corroborated by observable input data; and Level 3, defined as valuations based on unobservable inputs reflecting the Company’s own assumptions, consistent with reasonably available assumptions made by other market participants. The Company did not have any transfers of assets and liabilities between Level 1, Level 2, and Level 3 of the fair value hierarchy during the six months ended June 30, 2019 and the year ended December 31, 2018.

For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with the fair value hierarchy. Fair value measurements for assets and liabilities where there exists limited or no observable market data and therefore, are based primarily upon estimates, are often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures.

As prescribed by U.S. GAAP, the Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. An adjustment to the pricing method used within either Level 1 or Level 2 inputs could generate a fair value measurement that effectively falls in a lower level in the hierarchy.

The determination of where an asset or liability falls in the hierarchy requires significant judgment. The Company evaluates its hierarchy disclosures and based on various factors, it is possible that an asset or liability may be classified differently from period to period. However, the Company expects changes in classifications between levels will be rare.

The carrying values of accounts receivable, short-term investments, interest receivable, accounts payable, and certain accrued expenses at June 30, 2019 and December 31, 2018, approximate their fair values due to the short-term nature of these items. The Company’s notes payable balance also approximates fair value as of June 30, 2019 and December 31, 2018, as the interest rates on the notes payable approximate the rates available to the Company as of these dates.

The following are the major categories of assets and liabilities measured at fair value on a recurring basis as of June 30, 2019 and December 31, 2018, using quoted prices in active markets for identical assets (Level 1); significant other observable inputs (Level 2); and significant unobservable inputs (Level 3):



	June 30, 2019
	(In thousands) (unaudited)
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets measured at fair value
Cash and cash equivalents	$	23,302	$	—	$	—	$	23,302
Restricted cash	712		—		—		712
Total Assets measured at fair value	$	24,014	$	—	$	—	$	24,014
Liabilities measured at fair value
Contingent consideration	—		—		12,595		12,595
Warrant liabilities	—		—		2,214		2,214
Total liabilities measured at fair value	$	—	$	—	$	14,809	$	14,809



Description	December 31, 2018
	(In thousands)
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets measured at fair value
Cash and cash equivalents	$	21,061	$	—	$	—	$	21,061
Restricted cash	590		—		—		590
Total Assets measured at fair value	$	21,651	$	—	$	—	$	21,651
Liabilities measured at fair value
Contingent consideration	$	—	$	—	$	10,637	$	10,637
Warrant liabilities	—		—		4,636		4,636
Total liabilities measured at fair value	—		—		15,273		15,273

The Company’s financial liabilities consisted of contingent consideration potentially payable to Sofar related to the Senhance Acquisition in September 2015 (Note 3). This liability is reported as Level 3 as estimated fair value of the contingent consideration related to the acquisition requires significant management judgment or estimation and is calculated using the income approach, using various revenue and cost assumptions and applying a probability to each outcome. The change in fair value of the contingent consideration of $2.0 million for the six months ended June 30, 2019 was primarily due to the passage of time and a decrease in the discount rate used. The change in fair value of the contingent consideration of $1.4 million for the six months ended June 30, 2018 was primarily due to the passage of time on the fair value measurement and the impact of foreign currency exchange rates. Adjustments associated with the change in fair value of contingent consideration are included in the Company’s consolidated statements of operations and comprehensive loss.

On April 28, 2017, the Company sold 24.9 million units (the “Units”), each consisting of one share of the Company’s Common Stock, a Series A warrant to purchase one share of Common Stock with an exercise price of $1.00 per share (the “Series A Warrants”), and a Series B warrant to purchase 0.75 shares of Common Stock with an exercise price of $1.00 per Unit (the “Series B Warrants,” together with the Series A Warrants, the “Warrants”), at an offering price of $1.00 per Unit. Each Series A Warrant was exercisable at any time beginning on the date of issuance, and from time to time thereafter, through and including the first anniversary of the issuance date, unless terminated earlier as provided in the Series A Warrant. Receipt of 510(k) clearance for the Senhance System on October 13, 2017 triggered the acceleration of the expiration date of the Series A Warrants to October 31, 2017. Each Series B Warrant may be exercised at any time beginning on the date of issuance and from time to time thereafter through and including the fifth anniversary of the issuance date.

The fair value of the Series A Warrants of $2.5 million at the date of issuance was estimated using the Black-Scholes Merton model which used the following inputs: term of 1 year, risk free rate of 1.07%, no dividends, volatility of 73.14%, and share price of $0.65 per share based on the trading price of the Company’s Common Stock. All Series A Warrants were exercised as of October 31, 2017.

The change in fair value of all outstanding Series B Warrants for the six months ended June 30, 2019 was a decrease of $2.4 million compared to an increase of $15.7 million for the six months ended June 30, 2018, and is included in the Company’s consolidated statements of operations and comprehensive loss. The following table presents the inputs and valuation methodologies used for the Company’s fair value of the Series B Warrants:



Series B	June 30, 2019	December 31, 2018	April 28, 2017 (date of issuance)
Fair value	$2.2 milllion	$4.6 milllion	$6.2 milllion
Valuation methodology	Monte Carlo	Monte Carlo	Black-Scholes Merton
Term	2.8 years	3.3 years	5.0 years
Risk free rate	1.71%	2.47%	1.81%
Dividends	—	—	—
Volatility	82.34%	87.60%	73.14%
Share price	$1.36	$2.26	$0.65
Probability of additional financing	100% in 2019	100% in 2019	Not Applicable

The following table presents quantitative information about the inputs and valuation methodologies used for the Company’s fair value measurements classified in Level 3 with the exception of the warrant liability, which is explained above as of June 30, 2019 and December 31, 2018:



	Fair Value Measurement at Reporting Date (Level 3)
	(In thousands) (unaudited)
	Common stock warrants			Contingent consideration
Balance at December 31, 2018	$	4,636		$	10,637
Change in fair value	(2,422		)	1,958
Balance at June 30, 2019	$	2,214		$	12,595
Current portion	—			74
Long-term portion	2,214			12,521
Balance at June 30, 2019	$	2,214		$	12,595