Intangible Assets

12 Months Ended

Sep. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets at September 30 consisted of:


	2020				2019
(Millions of dollars)	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Amortized intangible assets
Developed technology	$	14,105	$	3,959	$	13,960	$	2,906
Customer relationships	4,616		1,509		4,608		1,183
Product rights	119		73		110		60
Trademarks	408		120		407		102
Patents and other	500		320		445		305
Amortized intangible assets	$	19,748	$	5,981	$	19,530	$	4,555

Unamortized intangible assets
Acquired in-process research and development (a)	$	44			$	1
Trademarks	2				2
Unamortized intangible assets	$	46			$	3

(a)The increase in the carrying value of assets in 2020 was attributable to an immaterial acquisition which occurred during the second quarter of fiscal year 2020.

Intangible amortization expense was $1.384 billion, $1.497 billion and $1.255 billion in 2020, 2019 and 2018, respectively. The increase in intangible amortization expense beginning in 2019 was attributable to the first full year amortization of assets acquired in the Bard transaction, which is further discussed in Note 10. The estimated aggregate amortization expense for the fiscal years ending September 30, 2021 to 2025 are as follows: 2021 — $1.387 billion; 2022 — $1.377 billion; 2023 — $1.359 billion; 2024 — $1.357 billion; 2025 — $1.357 billion.

The following is a reconciliation of goodwill by business segment:


(Millions of dollars)	Medical		Life Sciences		Interventional		Total
Goodwill as of September 30, 2018	$	10,054	$	775	$	12,771	$	23,600

Divestitures and related adjustments (a)	—		3		—		3

Purchase price allocation adjustments (b)	(15)		—		(75)		(90)
Currency translation	(50)		(6)		(81)		(137)
Goodwill as of September 30, 2019	$	9,989	$	772	$	12,615	$	23,376
Acquisitions (c)	10		58		49		117

Purchase price allocation adjustments	—		1		4		5
Currency translation	44		7		71		122
Goodwill as of September 30, 2020	$	10,044	$	837	$	12,739	$	23,620

(a)Represents adjustments to goodwill derecognized upon the Company's sale of certain businesses, as further discussed in Note 11.

(b)The purchase price allocation adjustments were primarily driven by adjustments to tax-related balances recorded upon the finalization of the Bard acquisition allocation within one year of the transaction's closing.

(c)Represents goodwill recognized relative to certain acquisitions which were not material individually or in the aggregate.