The carrying amounts of identifiable intangible assets are summarized as follows:


(in millions)	Indefinite-lived		Finite-lived			Total
December 31, 2023	$	17,578	$	680		$	18,258
Acquisition(1)		—		37			37
Amortization expense		—		(77	)		(77	)
Other		—		(1	)		(1	)
June 30, 2024	$	17,578	$	639		$	18,217

(1)

In connection with the SpiderRock Transaction, the Company acquired approximately $29 million of finite-lived customer relationships and $8 million of finite-lived technology-related intangible assets with weighted-average estimated lives of approximately eleven and five years, respectively.