Costco Wholesale Corp New (COST) SEC Filing 10-K Annual report for the fiscal year ending Sunday, September 2, 2018

Exhibit 99.1

Press Release

COSTCO WHOLESALE CORPORATION REPORTS FOURTH QUARTER AND

FISCAL YEAR 2018 OPERATING RESULTS

ISSAQUAH, Wash., October 4, 2018—Costco Wholesale Corporation (“Costco” or the “Company”) (Nasdaq: COST) today announced its operating results for the

Net sales for the 16-week fourth quarter were $43.4 billion, an increase of 5.0 percent from $41.4 billion in the 17-week fourth quarter last year. Net sales for the 52-week fiscal year were $138.4 billion, an increase of 9.7 percent from $126.2 billion in the 53-week fiscal year of 2017.

Comparable sales for the 16-week fourth quarter, and the 52-week fiscal year were as follows:

Comparable sales for these periods excluding the impacts from changes in gasoline prices and foreign exchange were as follows:

Net income for the 16-week fourth quarter was $1,043 million, or $2.36 per diluted share, compared to $919 million, or $2.08 per diluted share, in the 17-week fourth quarter last year.

Net income for the 52-week fiscal year was $3.13 billion, or $7.09 per diluted share, compared to $2.68 billion, or $6.08 per diluted share, in the 53-week prior year. Net income this year was positively impacted by a $41 million ($0.09 per diluted share) tax benefit in the first quarter, related to a change in accounting rules for stock-based compensation. Last year’s net income was positively impacted by an $82 million ($0.19 per diluted share) tax benefit in connection with the third-quarter special cash dividend and other net benefits of approximately $51 million ($0.07 per diluted share after tax) for nonrecurring legal and other matters.