Goodwill and Acquired Intangible Assets

12 Months Ended

Dec. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Acquired Intangible Assets

(4) Goodwill and Acquired Intangible Assets

The following table sets forth the changes in the carrying amount of goodwill for year ended December 31, 2019 (in thousands):

Balance, December 31, 2018	$	22,925
Effect of foreign currency		263
Balance, December 31, 2019	$	23,188

Acquired intangible assets consisted of the following at December 31, 2019 and 2018 (in thousands):

	As of December 31, 2019
	Amortization period (years)	Gross carrying amount		Accumulated amortization			Net carrying amount
Intellectual Property	7-15 years	$	16,584	$	(8,044	)	$	8,540
Trademarks	4.5 years		834		(834	)		-
Other	2-6 years		572		(553	)		19
In-process research and development	Indefinite		1,945		—			1,945
Total		$	19,935	$	(9,431	)	$	10,504

	As of December 31, 2018
	Amortization period (years)	Gross carrying amount		Accumulated amortization			Net carrying amount
Intellectual Property	7-15 years	$	16,509	$	(6,147	)	$	10,362
Trademarks	4.5 years		820		(820	)		—
Other	2-6 years		569		(505	)		64
In-process research and development	Indefinite		1,912		—			1,912
Total		$	19,810	$	(7,472	)	$	12,338

The weighted average amortization period of our finite-lived intangible assets is approximately 9 years. Amortization expense for the years ended December 31, 2019, 2018, and 2017 was $2.0 million, $2.0 million and $2.3 million, respectively. Amortization expense related to acquired intangibles is estimated at $1.9 million for each of 2020, 2021 and 2022, $1.4 million for 2023 and $0.3 million for 2024.

The acquired IPR&D asset relates to the six pre-clinical antibody programs acquired in the Agenus Switzerland transaction. IPR&D acquired in a business combination is capitalized at fair value until the underlying project is completed and is subject to impairment testing. Once the project is completed, the carrying value of IPR&D is amortized over the estimated useful life of the asset. Post-acquisition research and development expenses related to the acquired IPR&D are expensed as incurred.