What does market cap mean?
Market cap, short for market capitalization, is the stock market's value of a company's shares. It is the market price of one share times the total shares outstanding.[S1] Because it uses a price, it is always tied to a date.
How is market cap worked out?
Market cap = share price × shares outstanding.[S1]
Costco's Nasdaq closing price is $1,012.28 (price as of Oct 30, 2026).[S6] Its share count is 443.1 million (on Sep 29, 2026).[S5]
Price times shares gives $448.6B (price as of Oct 30, 2026)[S6][S5], shown in Costco's market context section. The price and the share count come from different dates.
The longer explainer, market cap and P/E in plain English, links market cap to the P/E ratio.
Where do you find it in a 10-K or 10-Q?
Neither form has a market cap line. Both cover pages give the shares outstanding of each class of common stock.[S2][S3]
The 10-K cover also states the market value of common equity held by non-affiliates. It uses the price on the last business day of the second fiscal quarter.[S2] Affiliates are holders that control the company, are controlled by it, or share a controller with it.[S4]
Costco's FY2026 10-K cover gives both figures, each on its own date.[S5]
What does market cap leave out?
- Debt and cash. It counts only shares, so what the company owes and holds sits in its balance sheet instead.[S1][S7]
- Affiliates' shares, on the 10-K cover. That figure is not the full market cap.[S2]
- Other share classes. Covers list each class separately.[S2] The share-count rows below show only companies with one class; see dual-class shares.
- Any other day. A new price gives a new market cap.[S1]