
	Cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
December 31, 2020
Short-term investments
Mutual fund	$	151,512	$	386	$	—	$	151,898
Bank deposits	84,120		35		(1)		84,154
Commercial paper	45,459		27		(1)		45,485
Corporate bonds	30,512		99		(1)		30,610
Agency bonds	4,499		2		—		4,501
Corporate equity securities	4,466		360		(1,388)		3,438
Treasury bill	3,999		—		—		3,999
Warrants	—		393		—		393
	$	324,567	$	1,302	$	(1,391)	$	324,478
December 31, 2019
Short-term investments
Bank deposits	$	411,690	$	188	$	(3)	$	411,875
Corporate bonds	63,818		161		—		63,979
Corporate equity securities	4,506		416		(1,850)		3,072
Commercial paper	210,525		43		(16)		210,552
Warrants	—		125		—		125
Mutual Fund	250,636		—		(249)		250,387
	$	941,175	$	933	$	(2,118)	$	939,990

In addition, as of December 31, 2020 and December 31, 2019, we recorded shares of Viking common stock we own at fair value of $32.8 million and $48.4 million, respectively, in “Short-term investments” in our consolidated balance sheets. We also own warrants to purchase up to 1.5 million shares of Viking's common stock at an exercise price of $1.50 per share. We recorded the warrants in “Short-term investments” in our consolidated balance sheet at fair value of $6.3 million and $9.9 million at December 31, 2020 and December 31, 2019, respectively.

Gain (loss) from short-term investments on our consolidated statements of operations includes both realized and unrealized gain (loss) from our short-term investments in public equity and warrant securities.


	December 31, 2020
	Amortized Cost		Fair Value
Within one year	$	141,732	$	141,793
After one year through five years	26,856		26,956
After five years	—		—
Total	$	168,588	$	168,749


	Less than 12 months				12 months or greater				Total
	Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value
December 31, 2020
Bank deposits	$	(1)	$	14,013	$	—	$	—	$	(1)	$	14,013
Corporate bonds	(1)		4,526		—		—		(1)		4,526
Commercial paper	(1)		7,693		—		—		(1)		7,693
Total	$	(3)	$	26,232	$	—	$	—	$	(3)	$	26,232

December 31, 2019
Bank deposits	$	(3)	$	58,584	$	—	$	—	$	(3)	$	58,584
Commercial paper	(16)		79,362		—		—		(16)		79,362
Total	$	(19)	$	137,946	$	—	$	—	$	(19)	$	137,946

Our investment policy is capital preservation and we only invested in U.S.-dollar denominated investments. We held a total of 14 positions which were in an unrealized loss position as of December 31, 2020. We believe that we will collect the principal and interest due on our debt securities that have an amortized cost in excess of fair value. The unrealized losses are largely due to changes in interest rates and not to unfavorable changes in the credit quality associated with these securities that impacted our assessment on collectability of principal and interest. We do not intend to sell these securities nor do we believe that we will be required to sell these securities before the recovery of the amortized cost basis. Accordingly, no credit losses were recognized for the twelve months ended December 31, 2020.


	December 31,
	2020		2019
Lab and office equipment	$	14,666	$	6,307
Leasehold improvements	3,519		2,729
Computer equipment and software	1,056		999
	19,241		10,035
Less accumulated depreciation and amortization	(4,807)		(2,850)
	$	14,434	$	7,185

Depreciation of equipment is computed using the straight-line method over the estimated useful lives of the assets which ranges from three to ten years. Leasehold improvements are amortized using the straight-line method over their estimated useful lives or their related lease term, whichever is shorter. Depreciation expense of $1.8 million, $1.5 million, and $0.9 million was recognized for the twelve months ended December 31, 2020, 2019, and 2018, respectively, and was included in operating expenses.


	As of December 31,
	2020		2019
Indefinite-lived intangible assets
Goodwill	$	189,662	$	95,229
Definite-lived intangible assets
Complete technology	277,740		242,813
Less: Accumulated amortization	(63,600)		(50,203)
Trade name	2,642		2,642
Less: Accumulated amortization	(1,312)		(1,180)
Customer relationships	40,700		29,600
Less: Accumulated amortization	(15,597)		(13,224)
Contractual relationships	362,000		—
Less: Accumulated amortization	(7,243)		—
Total goodwill and other identifiable intangible assets, net	$	784,992	$	305,677

Amortization of finite-lived intangible assets is computed using the straight-line method over the estimated useful life of the asset of 20 years. Amortization expense of $23.4 million, $16.9 million, and $15.8 million was recognized for the years ended December 31, 2020 and 2019, and 2018, respectively. Estimated amortization expense for the years ending December 31, 2021 through 2025 is $47.1 million per year. For each of the years ended December 31, 2020, 2019, and 2018, there was no material impairment of intangible assets with finite lives.


	December 31,
	2020		2019
Compensation	$	8,810	$	1,986
Professional fees	977		1,135
Amounts owed to former licensees	421		381
Royalties owed to third parties	693		—
Return reserve	687		3,027
Acquisition related liabilities	1,500		—
Subcontractor	733		—
Supplier	604		—
Other	4,105		2,052
	$	18,530	$	8,581

In connection with the acquisition of Crystal in October 2017, we entered into contingent liabilities based on achievement of certain research and business milestones as well as certain revenue goal.

In connection with the acquisition of CyDex in January 2011, we issued a series of CVRs and also assumed certain contingent liabilities. We may be required to make additional payments upon achievement of certain clinical and regulatory milestones to the CyDex shareholders and former license holders.

In connection with the acquisition of Metabasis in January 2010, we entered into four CVR agreements with Metabasis shareholders. The CVRs entitle the holders to cash payments as frequently as every six months as proceeds are received by us upon the sale or licensing of any of the Metabasis drug development programs and upon the achievement of specified milestones.


	December 31, 2018		Payments		Fair Value Adjustment		Repurchases		December 31, 2019		Additional Contingent Liabilities		Payments		Fair Value Adjustment		Repurchases		December 31, 2020
Cydex	$	514	$	(50)	$	(116)	$	—	$	348	$	—	$	—	$	160	$	—	$	508
Metabasis	5,551		—		904		(520)		5,935		—		—		(1,867)		(247)		3,821
Crystal	6,477		(3,000)		(818)		—		2,659		—		(1,800)		(59)		—		800
Icagen	—		—		—		—		—		4,800		(525)		2,129		—		6,404
Pfenex	—		—		—		—		—		37,000		—		600		—		37,600
Total	$	12,542	$	(3,050)	$	(30)	$	(520)	$	8,942	$	41,800	$	(2,325)	$	963	$	(247)	$	49,133