Goodwill and other intangible assets

Goodwill

Changes in the carrying amount of goodwill were as follows (in millions):



	Six months ended June 30, 2018
Beginning balance	$	14,761
Addition from K-A acquisition	6
Currency translation adjustment	(43		)
Ending balance	$	14,724

Other intangible assets

Other intangible assets consisted of the following (in millions):



	June 30, 2018							December 31, 2017
	Gross carrying amounts		Accumulated amortization			Intangible assets, net		Gross carrying amounts		Accumulated amortization			Intangible assets, net
Finite-lived intangible assets:
Developed-product-technology rights	$	12,581	$	(7,139	)	$	5,442	$	12,589	$	(6,796	)	$	5,793
Licensing rights	3,772		(1,810		)	1,962		3,275		(1,601		)	1,674
Marketing-related rights	1,303		(967		)	336		1,319		(920		)	399
R&D technology rights	1,155		(838		)	317		1,161		(804		)	357
Total finite-lived intangible assets	18,811		(10,754		)	8,057		18,344		(10,121		)	8,223
Indefinite-lived intangible assets:
In-process research and development	386		—			386		386		—			386
Total other intangible assets	$	19,197	$	(10,754	)	$	8,443	$	18,730	$	(10,121	)	$	8,609

Developed-product-technology rights consist of rights related to marketed products acquired in business combinations. Licensing rights consist primarily of contractual rights acquired in business combinations to receive future milestone, royalty and profit sharing payments; capitalized payments to third parties for milestones related to regulatory approvals to commercialize products; and up-front payments associated with royalty obligations for marketed products. During the six months ended June 30, 2018, licensing rights increased due to the K-A share acquisition. See Note 3, Business combinations. Marketing-related intangible assets consist primarily of rights related to the sale and distribution of marketed products. R&D technology rights consist of technology used in R&D with alternative future uses.

In-process research and development (IPR&D) consists of R&D projects acquired in a business combination that are not complete at the time of acquisition due to remaining technological risks and/or lack of receipt of required regulatory approvals. As of June 30, 2018, IPR&D consists primarily of the oprozomib project, acquired in the acquisition of Onyx Pharmaceuticals, Inc., in 2013.

All IPR&D projects have major risks and uncertainties associated with the timely and successful completion of the development and commercialization of product candidates, including our ability to confirm safety and efficacy based on data from clinical trials, our ability to obtain necessary regulatory approvals and our ability to successfully complete these tasks within budgeted costs. We are not permitted to market a human therapeutic without obtaining regulatory approvals, and such approvals require the completion of clinical trials that demonstrate that a product candidate is safe and effective. In addition, the availability and extent of coverage and reimbursement from third-party payers, including government healthcare programs and private insurance plans as well as competitive product launches, affect the revenues a product can generate. Consequently, the eventual realized value, if any, of acquired IPR&D projects may vary from their estimated fair values. We review IPR&D projects for impairment annually, whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable and upon the establishment of technological feasibility or regulatory approval.

During the three months ended June 30, 2018 and 2017, we recognized amortization expense associated with our finite-lived intangible assets of $332 million and $371 million, respectively. During the six months ended June 30, 2018 and 2017, we recognized amortization expense associated with our finite-lived intangible assets of $652 million and $744 million, respectively. Amortization of intangible assets is included primarily in Cost of sales in the Condensed Consolidated Statements of Income. The total estimated amortization expense for our finite-lived intangible assets for the remaining six months ending December 31, 2018, and the years ending December 31, 2019, 2020, 2021, 2022 and 2023, are $0.7 billion, $1.3 billion, $1.2 billion, $1.0 billion, $0.9 billion and $0.9 billion, respectively.