Goodwill and intangible assets acquired are recognized at fair value as of the acquisition date. The carrying amount of goodwill as of December 31, 2023 and 2022 was $17.9 million and $26.7 million, respectively. We have not recognized any impairment losses related to goodwill and intangible assets during the periods presented.

Intangible assets with definite lives are amortized over their estimated useful lives. The carrying basis and accumulated amortization of recognized intangible assets as of December 31, 2023 and 2022 were as follows:


	December 31, 2023
	Useful Life	Gross		Accumulated			Net Carrying
(In thousands)	(Years)	Amount		Amortization			Amount
Marketed products	8-10	$	219,700	$	(25,204	)	$	194,496
In-process research and development			2,600		—			2,600
Collaboration agreement	10		35,400		(2,161	)		33,239
Total		$	257,700	$	(27,365	)	$	230,335


	December 31, 2022
	Useful Life	Gross		Accumulated			Net Carrying
(In thousands)	(Years)	Amount		Amortization			Amount
Marketed products	8-10	$	151,000	$	(5,581	)	$	145,419
In-process research and development			72,100		—			72,100
Collaboration agreement			35,400		—			35,400
Total		$	258,500	$	(5,581	)	$	252,919

Intangible assets recognized as a result of the acquisition of Entasis amounted to $106.7 million, which consisted of Entasis’ in-process research and development related to its antibacterial therapeutic product candidates and a collaboration agreement amounting to $71.3 million and $35.4 million, respectively. Following the FDA approval of XACDURO® in May 2023, we started amortizing $68.7 million of the then in-process research and development as a marketed product, as well as the collaboration agreement, over their estimated useful lives. The useful life of the remaining in-process research and development of $2.6 million will be determined upon commercialization of the underlying product candidate; thus, no amortization expense for this intangible asset was recognized for the periods presented.

Intangible assets recognized as a result of the acquisition of La Jolla amounting to $151.0 million pertain to product rights and developed technologies on La Jolla’s currently marketed products. These are intangible assets with determinable lives and are amortized over their estimated useful lives.

We recognized amortization expense of $21.8 million and $5.6 million for the years ended December 31, 2023 and 2022, respectively. Future amortization expense is expected to be $25.8 million for each of the years from 2024 to 2028 and $98.7 million thereafter.