
	December 31, 2024
	Cost	Accumulated amortization	Net book value
	(in US $ millions)
Acquired technology	72	51	21
Other intangible assets	5	4	1
Software development costs	14	14	—
	91	69	22


	December 31, 2023
	Cost	Accumulated amortization	Net book value
	(in US $ millions)
Acquired technology	65	38	27
Other intangible assets	5	3	2
Software development costs	14	14	—

	84	55	29

During the years ended December 31, 2024 and 2023, the Company completed individually immaterial acquisitions that resulted in intangible assets being recognized.

During the year December 31, 2023, the Company recognized an impairment of $307 million of acquired technology, $27 million of acquired customer relationships and $3 million of other intangible assets as a result of the sales of Shopify's logistics businesses (see Note 4).

During the year ended December 31, 2023, the Company disposed of and retired software development costs, acquired technology and purchased software with a combined original cost of $440 million, primarily due to the sales of our logistics businesses (December 31, 2022 - $31 million). Other than the impairment charges noted above, there was no additional gain or loss recognized in the consolidated statement of operations and comprehensive income (loss) as a result of the retirement or disposal of these assets.

The following table illustrates the classification of amortization expense related to intangible assets in the consolidated statement of operations and comprehensive income (loss):


	Years ended
		December 31, 2024	December 31, 2023	December 31, 2022

		(in US $ millions)
Cost of revenues		12	35	49
Sales and marketing		1	3	5
Research and development		1	—	—

		14	38	54

Estimated future amortization expense related to intangible assets, as of December 31, 2024 is as follows: