*  Other intangibles are primarily acquired proprietary and non-proprietary business processes, methodologies and systems.

The net carrying amount of intangible assets increased $12,526 million during the first nine months of 2019, primarily due to the acquisition of Red Hat, partially offset by intangible asset amortization. Intangible assets of $13,472 million generated from the acquisition of Red Hat have been assigned to the segments as follows: Cloud & Cognitive Software $10,729 million, Global Technology Services $1,819 million, Global Business Services $617 million and Systems $306 million. For additional information on the acquisition of Red Hat, see note 11, “Acquisitions/Divestitures.”

The aggregate intangible amortization expense was $614 million and $1,224 million for the third quarter and first nine months of 2019, respectively, versus $348 million and $1,031 million for the third quarter and first nine months of 2018, respectively. In the first nine months of 2019, the company retired $543 million of fully amortized intangible assets, impacting both the gross carrying amount and accumulated amortization by this amount. In addition, in the first nine months of 2019, the company divested select intangible assets with a gross carrying amount of $317 million and $253 million of accumulated amortization.

​

The amortization expense for each of the five succeeding years relating to intangible assets currently recorded in the Consolidated Statement of Financial Position is estimated to be the following at September 30, 2019:

​

​

Goodwill

The change in the goodwill balances by segment, for the nine months ended September 30, 2019 and for the year ended December 31, 2018 are as follows:

​