The following table presents the changes in the carrying value of goodwill by reportable segment for the six months ended June 30, 2021 (in millions):


	Mobility		Delivery		Freight		Total Goodwill
Balance as of December 31, 2020	$	2,562	$	3,547	$	—	$	6,109
Acquisitions	98		53		—		151
Measurement period adjustment (1)	—		183		—		183

Foreign currency translation adjustment	6		(1)		—		5
Balance as of June 30, 2021	$	2,666	$	3,782	$	—	$	6,448

The components of intangible assets, net as of December 31, 2020 and June 30, 2021 were as follows (in millions, except years):


	Gross Carrying Value		Accumulated Amortization		Net Carrying Value		Weighted Average Remaining Useful Life - Years
December 31, 2020
Rider and Merchant relationships	$	1,007	$	(81)	$	926	8
Developed technology	529		(69)		460		2
Trade names and trademarks	183		(16)		167		7
Patents	15		(6)		9		8
Other	5		(3)		2		0
Intangible assets	$	1,739	$	(175)	$	1,564


	Gross Carrying Value		Accumulated Amortization		Net Carrying Value		Weighted Average Remaining Useful Life - Years
June 30, 2021
Rider and Merchant relationships	$	1,051	$	(172)	$	879	4
Developed technology	492		(158)		334		2
Trade names and trademarks	184		(30)		154		6
Patents	15		(6)		9		7
Other	5		(3)		2		0
Intangible assets	$	1,747	$	(369)	$	1,378

Amortization expense for intangible assets subject to amortization was $25 million and $104 million for the three months ended June 30, 2020 and 2021, respectively. Amortization expense for intangible assets subject to amortization was $53 million and $196 million for the six months ended June 30, 2020 and 2021, respectively.

The estimated aggregate future amortization expense for intangible assets subject to amortization as of June 30, 2021 is summarized below (in millions):


	Estimated Future Amortization Expense
Year Ending December 31,
Remainder of 2021	$	208
2022	359
2023	199
2024	152
2025	132
Thereafter	315
Total	$	1,365