Exhibit 99.1

Press Release

COSTCO WHOLESALE CORPORATION REPORTS SECOND QUARTER AND YEAR-TO-DATE

OPERATING RESULTS FOR FISCAL 2019 AND FEBRUARY SALES RESULTS

ISSAQUAH, Wash., March 7, 2019 - Costco Wholesale Corporation (“Costco” or the “Company”) (Nasdaq: COST) today announced its operating results for the second quarter (twelve weeks) and the first 24 weeks of fiscal 2019, ended February 17, 2019.

Net sales for the quarter increased 7.3 percent, to $34.63 billion from $32.28 billion last year. Net sales for the first 24 weeks increased 8.7 percent, to $68.94 billion from $63.40 billion last year.

Comparable sales for the second quarter and year-to-date periods ended February 17, 2019, were as follows:

Reported net income for the quarter was $889 million, or $2.01 per diluted share, compared to $701 million, or $1.59 per diluted share, last year. Net income for the first 24 weeks was $1.66 billion, or $3.74 per diluted share, compared to $1.34 billion, or $3.04 per diluted share, last year.

For the four-week reporting month of February, ended March 3, 2019, the Company reported net sales of $10.72 billion, an increase of 5.0 percent from $10.21 billion last year. For the twenty-six week period ended March 3, 2019, net sales were $74.42 billion, an increase of 8.6 percent from $68.51 billion last year.

Comparable sales for the February and year-to-date periods ended March 3, 2019, were as follows:

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February’s sales were negatively impacted approximately 1% by weather throughout the U.S. and Canada. In addition, Lunar New Year/Chinese New Year occurred eleven days earlier in February this year, negatively impacting February’s Other International sales by approximately 4.5% and Total Company sales by approximately 0.5%.

Costco currently operates 770 warehouses, including 535 in the United States and Puerto Rico, 100 in Canada, 39 in Mexico, 28 in the United Kingdom, 26 in Japan, 15 in Korea, 13 in Taiwan, 10 in Australia, two in Spain, and one each in Iceland and France. Costco also operates e-commerce sites in the U.S., Canada, the United Kingdom, Mexico, Korea, and Taiwan.

A conference call to discuss these results is scheduled for 2:00 p.m. (PT) today, March 7, 2019, and is available via a webcast on www.costco.com (click on Investor Relations and “Play Webcast”).

Certain statements contained in this document constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. For these purposes, forward-looking statements are statements that address activities, events, conditions or developments that the Company expects or anticipates may occur in the future. In some cases forward-looking statements can be identified because they contain words such as “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “likely,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “target,” “will,” “would,” or similar expressions and the negatives of those terms. Such forward-looking statements involve risks and uncertainties that may cause actual events, results or performance to differ materially from those indicated by such statements. These risks and uncertainties include, but are not limited to, domestic and international economic conditions, including exchange rates, the effects of competition and regulation, uncertainties in the financial markets, consumer and small business spending patterns and debt levels, breaches of security or privacy of member or business information, conditions affecting the acquisition, development, ownership or use of real estate, capital spending, actions of vendors, rising costs associated with employees (generally including health care costs), energy and certain commodities, geopolitical conditions (including tariffs), the ability to remediate material weaknesses in internal control, and other risks identified from time to time in the Company’s public statements and reports filed with the Securities and Exchange Commission. Forward-looking statements speak only as of the date they are made, and the Company does not undertake to update these statements, except as required by law.

CONTACTS:     Costco Wholesale Corporation

Press Release

COSTCO WHOLESALE CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(dollars in millions, except per share data)

(unaudited)

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COSTCO WHOLESALE CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(amounts in millions, except par value and share data)

(unaudited)

Subject to Reclassifications