The following table presents the changes in Goodwill for the nine months ended September 30, 2024:


(In millions)
Balance as of December 31, 2023	$	630
Acquired goodwill	397
Balance as of September 30, 2024	$	1,027

Acquired goodwill represents the excess of consideration transferred over the estimated fair value of the underlying net assets acquired resulting from RXO’s acquisition of Coyote. There were no cumulative goodwill impairments as of September 30, 2024.

Our identifiable intangible assets consist of customer relationships and trade names, all of which are definite-lived. We did not recognize any impairment of our identified intangible assets in the three and nine months ended September 30, 2024 and 2023, respectively.

The following table summarizes the balance of our identifiable intangible assets:


(In millions)	September 30, 2024		December 31, 2023
Customer relationships	$	680	$	186
Trade name	15		—


Total identifiable intangible assets, gross	695		186
Less: Accumulated amortization	(130)		(118)
Total identifiable intangible assets, net	$	565	$	68

Estimated future amortization expense for amortizable intangible assets for the next five years and thereafter is as follows:


(In millions)	Remaining 2024		2025		2026		2027		2028		Thereafter
Estimated amortization expense	$	17	$	50	$	45	$	44	$	41	$	368

Actual amounts of amortization expense may differ from estimated amounts due to changes in estimated fair value of intangibles acquired in the acquisition of Coyote during the one-year measurement period, changes in foreign currency exchange rates, additional intangible asset acquisitions, future impairment of intangible assets, accelerated amortization of intangible assets and other events.

Intangible asset amortization expense was $5 million and $11 million for the three and nine months ended September 30, 2024, respectively. Intangible asset amortization expense was $4 million and $10 million for the three and nine months ended September 30, 2023, respectively.