The following tables present the company's intangible asset balances by major asset class.

* Amounts as of June 30, 2021 and December 31, 2020 included a decrease in net intangible asset balances of $109 million and an increase of $279 million, respectively, due to foreign currency translation.

**	Other intangibles are primarily acquired proprietary and non-proprietary business processes, methodologies and systems.

The net carrying amount of intangible assets decreased $257 million during the first six months of 2021, primarily due to intangible asset amortization, partially offset by additions of acquired intangibles and capitalized software. The aggregate intangible asset amortization expense was $630 million and $1,251 million for the second quarter and first six months of 2021, respectively, compared to $623 million and $1,245 million for the second quarter and first six months of 2020, respectively. In the first six months of 2021, the company retired $420 million of fully amortized intangible assets, impacting both the gross carrying amount and accumulated amortization by this amount.

The future amortization expense relating to intangible assets currently recorded in the Consolidated Balance Sheet was estimated to be the following at June 30, 2021:


	Capitalized		Acquired
(Dollars in millions)	Software		Intangibles		Total
Remainder of 2021	$	330	$	956	$	1,287
2022		418		1,843		2,261
2023		217		1,530		1,748
2024		37		1,481		1,518
2025		—		1,460		1,460
Thereafter		—		5,267		5,267

Goodwill

The changes in the goodwill balances by segment for the six months ended June 30, 2021 and for the year ended December 31, 2020 were as follows:


									Foreign
									Currency
					Purchase				Translation
(Dollars in millions)	Balance		Goodwill		Price				and Other		Balance
Segment	1/1/2021		Additions		Adjustments			Divestitures	Adjustments*		6/30/2021
Cloud & Cognitive Software	$	43,934	$	1,660	$	6	$	(2)	$	(136)	$	45,461
Global Business Services		6,145		616		(11)		—		(43)		6,706
Global Technology Services		7,245		2		—		—		(62)		7,184
Systems		2,293		—		0		—		0		2,293
Total	$	59,617	$	2,278	$	(6)	$	(2)	$	(242)	$	61,645


									Foreign
									Currency
					Purchase				Translation
(Dollars in millions)	Balance		Goodwill		Price				and Other		Balance
Segment	1/1/2020		Additions		Adjustments			Divestitures	Adjustments*		12/31/2020
Cloud & Cognitive Software	$	43,037	$	362	$	(139)	$	—	$	675	$	43,934
Global Business Services		5,775		205		—		—		165		6,145
Global Technology Services		7,141		—		—		—		104		7,245
Systems		2,270		8		—		—		15		2,293
Total	$	58,222	$	575	$	(139)	$	—	$	960	$	59,617

* Primarily driven by foreign currency translation.

There were no goodwill impairment losses recorded during the first six months of 2021 or full-year 2020 and the company has no accumulated impairment losses. Purchase price adjustments recorded in the first six months of 2021 and full-year 2020 were related to acquisitions that were still subject to the measurement period that ends at the earlier of 12 months from the acquisition date or when information becomes available. Net purchase price adjustments recorded in the first six months of 2021 were not material. In full-year 2020, net purchase price adjustments recorded to noncurrent tax assets and liabilities were related to the Red Hat acquisition.