Segments

The Company is engaged in retail and wholesale operations located in the U.S., Argentina, Brazil, Canada, Chile, China, India, Japan, Mexico and the United Kingdom, as well as countries located in Africa and Central America. The Company's operations are conducted in three business segments: Walmart U.S., Walmart International and Sam's Club. The Company defines its segments as those operations whose results its chief operating decision maker ("CODM") regularly reviews to analyze performance and allocate resources. The Company sells similar individual products and services in each of its segments. It is impractical to segregate and identify revenues for each of these individual products and services.

The Walmart U.S. segment includes the Company's mass merchant concept in the U.S. operating under the "Walmart" or "Wal-Mart" brands, as well as digital retail. The Walmart International segment consists of the Company's operations outside of the U.S., including various retail websites. The Sam's Club segment includes the warehouse membership clubs in the U.S., as well as digital retail. Corporate and support consists of corporate overhead and other items not allocated to any of the Company's segments.

The Company measures the results of its segments using, among other measures, each segment's net sales and operating income, which includes certain corporate overhead allocations. From time to time, the Company revises the measurement of each segment's operating income, including any corporate overhead allocations, as determined by the information regularly reviewed by its CODM. When the measurement of a segment changes, previous period amounts and balances are reclassified to be comparable to the current period's presentation.

Net sales by segment are as follows:



	Three Months Ended October 31,				Nine Months Ended October 31,
(Amounts in millions)	2017		2016		2017		2016
Net sales:
Walmart U.S.	$	77,724	$	74,550	$	231,898	$	224,086
Walmart International	29,548		28,390		84,976		85,094
Sam's Club	14,864		14,236		43,737		42,387
Net sales	$	122,136	$	117,176	$	360,611	$	351,567

Operating income by segment, as well as operating loss for corporate and support, interest, net, and loss on extinguishment of debt are as follows:



	Three Months Ended October 31,						Nine Months Ended October 31,
(Amounts in millions)	2017			2016			2017			2016
Operating income (loss):
Walmart U.S.	$	4,030		$	3,999		$	12,917		$	12,750
Walmart International	1,249			1,354			4,004			4,245
Sam's Club	447			396			1,265			1,281
Corporate and support	(962		)	(630		)	(2,216		)	(1,717		)
Operating income	4,764			5,119			15,970			16,559
Interest, net	541			585			1,679			1,712
Loss on extinguishment of debt	1,344			—			2,132			—
Income before income taxes	$	2,879		$	4,534		$	12,159		$	14,847