The following table presents the company's intangible asset balances by major asset class.

* Amounts as of March 31, 2021 and December 31, 2020 include a decrease in net intangible asset balances of $137 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 $261 million during the first three months of 2021, primarily due to intangible asset amortization, partially offset by additions of acquired intangibles and capitalized software. The aggregate intangible amortization expense was $620 million and $622 million for the quarters ended March 31, 2021 and 2020, respectively. In the first three months of 2021, the company retired $256 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 is estimated to be the following at March 31, 2021:


	Capitalized		Acquired
(Dollars in millions)	Software		Intangibles		Total
Remainder of 2021	$	469	$	1,379	$	1,848
2022		368		1,774		2,142
2023		168		1,459		1,627
2024		12		1,408		1,420
2025		—		1,389		1,389
Thereafter		—		5,109		5,109

Goodwill

The changes in the goodwill balances by segment for the three months ended March 31, 2021 and for the year ended December 31, 2020 are as follows:


							Foreign
							Currency
					Purchase		Translation
(Dollars in millions)	Balance		Goodwill		Price		and Other		Balance
Segment	1/1/2021		Additions		Adjustments		Adjustments*		3/31/2021
Cloud & Cognitive Software	$	43,934	$	245	$	6	$	(249)	$	43,935
Global Business Services		6,145		501		0		(61)		6,585
Global Technology Services		7,245		—		—		(70)		7,175
Systems		2,293		—		0		(4)		2,289
Total	$	59,617	$	746	$	6	$	(384)	$	59,984


							Foreign
							Currency
					Purchase		Translation
(Dollars in millions)	Balance		Goodwill		Price		and Other		Balance
Segment	1/1/2020		Additions		Adjustments		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 three months of 2021 or full-year 2020 and the company has no accumulated impairment losses. Purchase price adjustments recorded in the first three 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 during the first three 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.