Reconciliations of the changes in the carrying value of goodwill during 2025 and 2024 follow (in millions).


	December 31,
	2025			2024
Balance at the beginning of the year*	$	83,880		$	84,626
Business acquisitions		459			87
Other, including impairments and foreign currency translation		(1,265	)		(833	)
Balance at the end of the year*	$	83,074		$	83,880

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* Net of accumulated goodwill impairments of $13.0 billion as of December 31, 2025, $11.5 billion as of December 31, 2024 and $11.1 billion as of December 31, 2023.

Other intangible assets are summarized below (in millions).


	December 31, 2025						December 31, 2024
	Gross carrying amount		Accumulated amortization		Net carrying value		Gross carrying amount		Accumulated amortization		Net carrying value
Insurance and other:
Customer relationships	$	31,215	$	9,638	$	21,577	$	30,941	$	8,840	$	22,101
Trademarks and trade names		9,007		1,143		7,864		9,007		1,041		7,966
Patents and technology		5,237		4,196		1,041		5,375		4,359		1,016
Other		5,608		2,288		3,320		5,551		1,996		3,555
	$	51,067	$	17,265	$	33,802	$	50,874	$	16,236	$	34,638
Railroad, utilities and energy:*
Customer relationships and contracts	$	1,541	$	809	$	732	$	1,553	$	728	$	825
Other		442		134		308		437		126		311
	$	1,983	$	943	$	1,040	$	1,990	$	854	$	1,136

——————

* Included in other assets.

Intangible assets with indefinite lives were $18.9 billion as of December 31, 2025 and December 31, 2024 and primarily related to certain customer relationships and trademarks and trade names. Intangible asset amortization expense was $1.7 billion in 2025 and $1.8 billion in 2024 and 2023. Estimated amortization expense over the next five years follows (in billions): 2026 – $1.7; 2027 – $1.6; 2028 – $1.4; 2029 – $1.4 and 2030 – $1.3.