Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, “Intangibles—Goodwill and Other,” on December 31 of each fiscal year unless interim indicators of impairment exist. Goodwill is considered to be impaired when the net book value of a reporting unit exceeds its estimated fair value.

Teradyne has the option to perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If Teradyne determines this is the case, Teradyne is required to perform a quantitative goodwill impairment test to identify potential goodwill impairment and measure the amount of goodwill impairment loss to be recognized. If Teradyne determines that it is more likely than not that the fair value of the reporting unit is greater than its carrying amounts, the quantitative goodwill impairment test is not required. In performing the quantitative goodwill impairment test, Teradyne determines the fair value of a reporting unit using the results derived from an income approach and a market approach, weighting the fair value determined under each approach to determine an estimated fair value for a reporting unit. The income approach is estimated through the discounted cash flows (“DCF”) analysis. Determining fair value requires the exercise of significant judgment, including judgments about appropriate discount rates, perpetual growth rates, and the amount and timing of expected future cash flows. Discount rates are based on a weighted average cost of capital (“WACC”), which represents the average rate a business must pay its providers of debt and equity, plus a risk premium. The WACC used to test goodwill is derived from a group of comparable companies. The cash flows employed in the DCF analysis are derived from internal forecasts and external market forecasts. The market approach estimates the fair value of the reporting unit by utilizing the market comparable method which is based on revenue and earnings multiples from comparable companies. If the estimated fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired. If the carrying amount of a reporting unit exceeds its estimated fair value, then the goodwill is written down by the amount that carrying value exceeds the fair value of the reporting unit, but not below zero.

In the fourth quarter of 2023, Teradyne performed the annual goodwill impairment test, completing a quantitative assessment for the Robotics reporting unit and a qualitative assessment for the Wireless Test and System Test reporting units. There was no impairment as a result of the annual test performed in the fourth quarter of 2023. Key assumptions in the goodwill valuation model are forecasted revenues, discount rate, earnings before interest and taxes, and revenue multiples from comparable companies. A change in any of these key assumptions could result in the reporting unit being impaired in a future period.

In the fourth quarter of 2022, Teradyne performed the annual goodwill impairment test, completing a quantitative assessment for the Robotics reporting unit and a qualitative assessment for the Wireless Test and System Test reporting units. There was no impairment as a result of the annual test performed in the fourth quarter of 2022. Key assumptions in the goodwill valuation model are forecasted revenues, discount rate, earnings before interest and taxes, and revenue multiples from comparable companies.

The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2023 and 2022 are as follows:


	Robotics			Wireless Test			Semiconductor Test			System Test			Total
	(in thousands)
Balance at December 31, 2021:
Goodwill	$	405,971		$	361,819		$	262,101		$	158,699		$	1,188,590
Accumulated impairment losses		—			(353,843	)		(260,540	)		(148,183	)		(762,566	)
		405,971			7,976			1,561			10,516			426,024
Foreign currency translation adjustment		(22,805	)		—			(24	)		—			(22,829	)
Balance at December 31, 2022:
Goodwill		383,166			361,819			262,077			158,699			1,165,761
Accumulated impairment losses		—			(353,843	)		(260,540	)		(148,183	)		(762,566	)
		383,166			7,976			1,537			10,516			403,195
Foreign currency translation adjustment		12,297			—			160			—			12,457
Balance at December 31, 2023:
Goodwill		395,463			361,819			262,237			158,699			1,178,218
Accumulated impairment losses		—			(353,843	)		(260,540	)		(148,183	)		(762,566	)
	$	395,463		$	7,976		$	1,697		$	10,516		$	415,652

Teradyne reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful lives of these assets are no longer appropriate.

There were no events or circumstances indicating that the carrying value of intangible and long-lived assets may not be recoverable in 2023, 2022 and 2021.

Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets:


	December 31, 2023
	Gross Carrying Amount (1)		Accumulated Amortization (1)			Foreign Currency Translation Adjustment			Net Carrying Amount
	(in thousands)
Developed technology	$	267,706	$	(243,191	)	$	(5,343	)	$	19,172
Customer relationships		52,109		(47,850	)		232			4,491
Tradenames and trademarks		59,007		(46,021	)		(1,245	)		11,741
Total intangible assets	$	378,822	$	(337,062	)	$	(6,356	)	$	35,404


	December 31, 2022
	Gross Carrying Amount (1)		Accumulated Amortization (1)			Foreign Currency Translation Adjustment			Net Carrying Amount
	(in thousands)
Developed technology	$	270,967	$	(234,208	)	$	(5,935	)	$	30,824
Customer relationships		57,739		(51,186	)		172			6,725
Tradenames and trademarks		59,387		(41,930	)		(1,528	)		15,929
Total intangible assets	$	388,093	$	(327,324	)	$	(7,291	)	$	53,478

(1)

In 2023 and 2022, $9.3 million and $1.6 million, respectively, of amortizable intangible assets became fully amortized and have been eliminated from the gross carrying amount and accumulated amortization.

Aggregate intangible assets amortization expense for the years ended December 31, 2023, 2022, and 2021, was $19.0 million, $19.3 million, and $21.5 million, respectively. Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: