The following tables summarize the Company’s intangible assets (dollars in thousands):


	September 30, 2024
	Weighted average amortization period in years		Gross carrying amount		Accumulated amortization		Net carrying amount

Intangible Assets
Amortizing intangible assets:
Customer Relationships		15	$	36,600	$	6,862	$	29,738
Trade Names		10		800		225		575
Developed Technology		5		739		474		265
Vendor Relationships		15		1,265		398		867
Database		5		2,400		1,350		1,050
Patents		17		157		58		99
Subtotal intangible assets				41,961		9,367		32,594
In-place Lease Intangible Asset		4		568		397		171
Above Market Lease Intangible Asset		4		896		622		274
Total intangible assets			$	43,425	$	10,386	$	33,039


	December 31, 2023
	Weighted average amortization period in years		Gross carrying amount		Accumulated amortization		Net carrying amount
Intangible Assets
Amortizing intangible assets:
Customer Relationships		15	$	36,600	$	5,030	$	31,570
Trade Names		10		800		165		635
Developed Technology		5		739		349		390
Vendor Relationships		15		1,273		336		937
Database		5		2,400		990		1,410
Patents		17		157		51		106
Subtotal intangible assets				41,969		6,921		35,048
In-place Lease Intangible Asset		4		568		287		281
Above Market Lease Intangible Asset		4		896		457		439
Total intangible assets			$	43,433	$	7,665	$	35,768

The following table provides a roll forward of the carrying amount of goodwill (in thousands):



	2024			2023

Balance as of January 1:
Gross goodwill	$	265,989		$	261,110
Accumulated impairments		(3,074	)		(3,074	)
Net goodwill as of January 1		262,915			258,036
Goodwill acquired during the year(1)		—			4,836
Impact of foreign exchange		40			43
Net goodwill as of September 30, 2024 and December 31, 2023:	$	262,955		$	262,915

(1) See Note 7 - Acquisitions.

As of September 30, 2024 and December 31, 2023, Xometry had $263.0 million and $262.9 million, respectively of goodwill. As of September 30, 2024 and December 31, 2023, $258.0 million was part of Xometry’s U.S. operating segment and $4.9 million was part of Xometry’s International operating segment.

As of September 30, 2024, estimated amortization expense for intangible assets for the remainder of 2024 and the next five years is: $0.9 million in 2024, $3.6 million in 2025, $3.2 million in 2026, $2.6 million in 2027, $2.6 million in 2028, $2.6 million in 2029 and $17.5 million thereafter.

Amortization expense for the three and nine months ended September 30, 2024 and 2023 was as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Sales and marketing	$	770		767	$	2,310		2,347
Product development		42		42		126		126
General and administrative (1)		4		7		11		20
Total	$	816	$	816	$	2,447	$	2,493

(1) Amortization of the lease related intangible assets is recorded as operating lease expense in general and administrative.