CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS

Securities classified as cash and cash equivalents and short-term investments as of December 31, 2018 and 2017 are summarized below (in thousands). Estimated fair value is based on quoted market prices for these investments.



December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	95,660	$	—	$	—	$	95,660
Money market funds	11		—		—		11
Agency Bond	1,250						1,250
Commercial paper	14,028		—		—		14,028
Total cash and cash equivalents	110,949		—		—		110,949



December 31, 2017	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash and cash equivalents:
Cash	$	103,119	$	—	$	—		$	103,119
Money market funds	95		—		—			95
Commercial paper	23,670		—		—			23,670
Total cash and cash equivalents	126,884		—		—			126,884
Short-term investments
Corporate debt securities and commercial paper with maturities less than 1 year	1,210		—		(5		)	1,205
Total short-term investments	1,210		—		(5		)	1,205
Total	$	128,094	$	—	$	(5	)	$	128,089

The Company considers all highly liquid investments with a maturity at date of purchase of three months or less to be cash equivalents. Cash and cash equivalents generally consist of cash on deposit with banks, money market instruments, U.S. Agency discount notes, commercial paper and corporate debt securities.

The Company invests its cash in money market funds and marketable securities including U.S. Treasury and government agency securities, commercial paper, and high quality debt securities of financial and commercial institutions. To date, the Company has not experienced material losses on any of its balances. These securities are carried at fair value, which is based on readily available market information, with unrealized gains and losses included in “accumulated other comprehensive loss” within shareholders’ equity on the consolidated balance sheets. The Company uses the specific identification method to determine the amount of realized gains or losses on sales of marketable securities. Realized gains or losses have been insignificant and are included in “interest and other income” in the consolidated statement of operations.

At December 31, 2018, the Company had zero securities in an unrealized loss position. The following table shows the gross unrealized losses and fair value of the Company’s investments with unrealized losses that are not deemed to be other‑than‑temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2017 (in thousands):



	Less than 12 months					12 months or greater				Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Corporate debt securities	$	1,205	$	(5	)	$	—	$	—	$	1,205	$	(5	)

The gross unrealized losses above were caused by interest rate increases. No significant facts or circumstances have arisen to indicate that there has been any deterioration in the creditworthiness of the issuers of the securities held by the Company. Based on the Company’s review of these securities, including the assessment of the duration and severity of the unrealized losses and the Company’s ability and intent to hold the investments until maturity, there were no material other‑than‑temporary impairments for these securities at December 31, 2018. Gross realized gains and losses on marketable securities were not material for the years ended December 31, 2018, 2017 and 2016.

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.


•	Level 1: Quoted prices in active markets for identical assets or liabilities.


•	Level 2: Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.


•	Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2018 (in thousands):



December 31, 2018	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	11	$	—	$	—	$	11
Agency bond	—		1,250		—		1,250
Commercial paper	—		14,028		—		14,028
Collegium warrants			8,784				8,784
Total	$	11	$	24,062	$	—	$	24,073
Liabilities:
Contingent consideration—Zipsor	$	—	$	—	$	531	$	531
Contingent consideration—CAMBIA	—		—		507		507
Total	$	—	$	—	$	1,038	$	1,038

The fair value of the warrants to purchase Collegium’s common stock was calculated using the Black-Scholes option pricing model. As of November 8, 2018, the significant inputs included the fair value of Collegium’s common stock of $15.56, an expected term of 4 years and a risk-free rate of 3.05%. As of December 31, 2018, the significant inputs included the fair value of Collegium’s common stock of $17.17, an expected term of 3.86 years and a risk-free rate of 2.48%. The expected term was based on the remaining contractual period of 3.86 years, and the volatility was determined using Collegium’s historical common stock volatility over the expected term.

The fair value measurement of the contingent consideration obligations arises from the Zipsor, CAMBIA and Lazanda acquisitions and relates to fair value of the potential future contingent milestone payments and royalties payable under the respective agreements which are determined using Level 3 inputs. The remaining contingent consideration liability following the divestiture of Lazanda in November 2017 was $0.2 million. This liability was settled in the first quarter of 2018. The key assumptions in determining the fair value are the discount rate and the probability assigned to the potential milestones and royalties being achieved. At each reporting date, the Company re-measures the contingent consideration obligation arising from the above acquisitions to their estimated fair values. Any changes in the fair value of contingent consideration resulting from a change in the underlying inputs are recognized in operating expenses until the contingent consideration arrangement is settled. Changes in the fair value of contingent consideration resulting from the passage of time are recorded within interest expense until the contingent consideration is settled.

The table below provides a summary of the changes in fair value recorded in interest expense, selling, general and administrative expense, and gain on divestiture of Lazanda measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2018, 2017 and 2016 (in thousands):



	December 31,
	2018			2017			2016
Fair value, beginning of the period	$	1,613		$	14,825		$	14,971
Changes in fair value recorded in interest expense	124			1,079			2,408
Changes in fair value recorded in selling, general and administrative expenses	(515		)	(7,708		)	(122		)
Royalties and milestone paid	(184		)	(3,068		)	(2,432		)
Divestiture of Lazanda	—			(3,515		)	—
Total	$	1,038		$	1,613		$	14,825

The estimated fair value of the 2.50% Convertible Senior Notes Due 2021, which the Company issued on September 9, 2014 (the 2021 Notes), is based on a market approach. The estimated fair value was approximately $231.8 million (par value $345.0 million) as of December 31, 2018 and represents a Level 2 valuation. The principal amount of the Senior Notes approximates their fair value as of December 31, 2018 and represents a Level 2 valuation. When determining the estimated fair value of the Company’s debt, the Company uses a commonly accepted valuation methodology and market-based risk measurements that are indirectly observable, such as credit risk.

There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the years ended December 31, 2018 and December 31, 2017.

The following table represents the Company’s fair value hierarchy for its financial assets measured at fair value on a recurring basis as of December 31, 2017 (in thousands):



December 31, 2017	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	95	$	—	$	—	$	95
Commercial paper	—		23,670		—		23,670
Corporate debt securities	—		1,205		—		1,205
Total	$	95	$	24,875	$	—	$	24,970
Liabilities:
Contingent consideration—Zipsor	$	—	$	—	$	464	$	464
Contingent consideration—Lazanda	—		—		156		156
Contingent consideration—CAMBIA	—		—		993		993
	$	—	$	—	$	1,613	$	1,613