Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2021

Equity [Abstract]

Stock-Based Compensation Expense

Stock-based compensation expense is as follows (in millions):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2021		2020		2021
Cost of sales	$	75	$	126	$	193	$	361
Fulfillment	316		473		993		1,381
Technology and content	1,267		1,627		3,649		4,742
Marketing	446		657		1,233		1,804
General and administrative	184		297		578		789
Total stock-based compensation expense	$	2,288	$	3,180	$	6,646	$	9,077

Restricted Stock Unit Activity

The following table summarizes our restricted stock unit activity for the nine months ended September 30, 2021 (in millions):

	Number of Units	Weighted-Average Grant-Date Fair Value
Outstanding as of December 31, 2020	15.2	$	2,004
Units granted	5.7	3,334
Units vested	(3.7)	1,624
Units forfeited	(1.6)	2,232
Outstanding as of September 30, 2021	15.6	2,552

Scheduled Vesting for Outstanding Restricted Stock Units

Scheduled vesting for outstanding restricted stock units as of September 30, 2021, is as follows (in millions):

	Three Months Ended December 31,	Year Ended December 31,
	2021	2022	2023	2024	2025	Thereafter	Total
Scheduled vesting — restricted stock units	1.8	5.5	5.2	2.1	0.7	0.3	15.6

Changes in Stockholders' Equity

The following table shows changes in stockholders’ equity (in millions):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2021		2020		2021
Total beginning stockholders’ equity	$	73,728	$	114,803	$	62,060	$	93,404
Beginning and ending common stock	5		5		5		5
Beginning and ending treasury stock	(1,837)		(1,837)		(1,837)		(1,837)
Beginning additional paid-in capital	38,017		48,724		33,658		42,865
Stock-based compensation and issuance of employee benefit plan stock	2,290		3,155		6,649		9,014
Ending additional paid-in capital	40,307		51,879		40,307		51,879
Beginning accumulated other comprehensive income (loss)	(1,455)		(525)		(986)		(180)
Other comprehensive income (loss)	426		(550)		(43)		(895)
Ending accumulated other comprehensive income (loss)	(1,029)		(1,075)		(1,029)		(1,075)
Beginning retained earnings	38,998		68,436		31,220		52,551
Net income	6,331		3,156		14,109		19,041
Ending retained earnings	45,329		71,592		45,329		71,592
Total ending stockholders’ equity	$	82,775	$	120,564	$	82,775	$	120,564