Goodwill represents the difference between the purchase price and the estimated fair value of identifiable assets acquired and liabilities assumed. Goodwill acquired in a business combination and determined to have an indefinite useful life is not

amortized, but instead is tested for impairment at least annually in accordance with ASC 350, “Intangibles – Goodwill and Other”. The following table represents the change in the carrying value of goodwill for the nine months ended September 30, 2021 (amounts in thousands):

During each of the fourth quarters of 2020, 2019 and 2018, the Company completed its annual impairment assessments and concluded that goodwill was not impaired in any of those years. The Company has not identified any “triggering” events which indicate an impairment of goodwill in the three and nine months ended September 30, 2021.

Intangible assets with a definitive life are amortized over their useful lives using the straight-line method, and the amortization expense is recorded within cost of product revenue and SG&A expenses in the Company’s statements of comprehensive income. Intangible assets and their related useful lives are reviewed at least annually to determine if any adverse conditions existed that would indicate the carrying value of these assets may not be recoverable. More frequent impairment assessments are conducted if certain conditions exist, including a change in the competitive landscape, any internal decisions to pursue new or different technology strategies, a loss of a significant customer, or a significant change in the marketplace, including changes in the prices paid for our products or changes in the size of the market for the Company’s products. An impairment results if the carrying value of the asset exceeds the estimated fair value of the asset. If the estimate of an intangible asset’s remaining useful life is changed, the remaining carrying amount of the intangible asset is amortized prospectively over the revised remaining useful life. The Company continues to believe that its intangible assets are recoverable at September 30, 2021.

Indefinite-lived assets are reviewed for impairment at least annually. There has been no impairment of the Company’s intangible assets for the periods presented.

Intangible assets, net consisted of the following at September 30, 2021:


	September 30, 2021
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life (in years)
	(Amounts in thousands)
Finite-lived intangible assets:
Technology - developed	$	141,039	$	(19,426	)	$	121,613		17
Patents		240		(240	)		—		8
Customer relationships		257,297		(47,363	)		209,934		15
Trademarks		7,367		(771	)		6,596		19
Other intangibles		2,826		(1,506	)		1,320		4
Total finite-lived intangible assets		408,769		(69,306	)		339,463		16
Indefinite-lived intangible asset:
Trademarks		700		—			700		—
Total intangible assets	$	409,469	$	(69,306	)	$	340,163

Intangible assets consisted of the following at December 31, 2020:


	December 31, 2020
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life (in years)
	(Amounts in thousands)
Finite-lived intangible assets:
Technology - developed	$	114,217	$	(14,444	)	$	99,773		17
Patents		240		(240	)		—		8
Customer relationships		217,790		(37,333	)		180,457		16
Trademarks		5,893		(541	)		5,352		20
Other intangibles		2,142		(1,324	)		818		3
Total finite-lived intangible assets		340,282		(53,882	)		286,400		16
Indefinite-lived intangible asset:
Trademarks		700		—			700		—
Total intangible assets	$	340,982	$	(53,882	)	$	287,100

Amortization expense for finite-lived intangible assets was $5.7 million and $4.0 million for each of the three months ended September 30, 2021 and 2020, respectively, and $16.1 million and $11.8 million for each of the nine months ended September 30, 2021 and 2020, respectively. As of September 30, 2021, the Company expects to record the following amortization expense in future periods (amounts in thousands):