When headlines say a company “lost $100 billion in value,” it can sound as if $100 billion physically disappeared from its bank account.
That is not what happened.
Market capitalization is simply share price multiplied by shares outstanding. The SEC’s Investor.gov defines it as the market price of one share multiplied by the total number of outstanding shares.
Because one part of that equation: the stock price can change every second, market cap can move dramatically even while factories, employees, sales and cash balances barely change.
Nike provides a striking example.
Its market cap fell from about $264 billion at the end of 2021 to roughly $57 billion by September 2026, a decline of more than $200 billion. Yet Nike still generates around $46.4 billion in trailing revenue, which is roughly flat year over year.
The stock market has therefore repriced Nike far more aggressively than Nike’s actual business has contracted.
Market Cap Is Set at the Margin
Imagine a company with 1 billion shares outstanding.
If its shares trade at $100:
Market cap = $100 billion
If sellers push the latest trading price down to $90:
Market cap = $90 billion
The company has instantly “lost” $10 billion of market value.
But investors did not need to sell $10 billion worth of stock to make that happen.
Only a fraction of the company’s shares may have traded at the new price. The market then applies that latest price to every outstanding share when calculating market capitalization.
That same principle applies in crypto. Coinpaper’s explainer on crypto market-cap rankings shows how an asset’s calculated value can rise by billions without billions of dollars of fresh capital actually entering the market.
Why the Market Can Reprice a Business So Quickly
Stocks represent expectations about the future, not simply the company’s current sales.
Two companies earning the same revenue can receive very different valuations if investors expect one to grow faster, earn higher margins or face less competition.
That is why valuation multiples matter.
Nike’s price-to-sales ratio, for example, has fallen from roughly 4.0 in fiscal 2022 to about 1.2 today. Its price-to-book and price-to-earnings ratios have also compressed sharply.
Investors are therefore not simply saying Nike sells fewer shoes.
They are assigning a lower price to each dollar of Nike’s sales and earnings.
That repricing reflects concerns around slower growth, competition, China and the company’s turnaround strategy. Nike’s decline below $40 in 2026 left the stock nearly 78% below its 2021 record high, even though the underlying company remains one of the world’s largest sportswear businesses.
Our coverage of the Nike selloff illustrates how quickly investor expectations can change.
Market Cap Is Not the Same as Business Value
Market cap is useful, but it is only one valuation measure.
Investors also look at enterprise value, which adjusts market cap for debt and cash. Enterprise value can be more useful when comparing companies with very different capital structures.
Revenue measures sales.
Profit measures what remains after expenses.
Cash flow measures actual cash generation.
Market cap measures what equity investors are willing to pay today for the company’s shares.
| Metric | What it measures |
|---|---|
| Market cap | Share price × shares outstanding |
| Revenue | Total sales |
| Net income | Profit after expenses |
| Enterprise value | Equity value adjusted for debt and cash |
| Cash flow | Cash generated or consumed by the business |
This distinction matters whenever headlines claim billions have been “wiped out.”
The money has not necessarily left the company, and the same amount of investor cash has not necessarily disappeared.
Instead, the market has changed the price it is willing to assign to every share.
That is why a business can look broadly similar on Monday while its market capitalization is tens of billions of dollars smaller by Friday.
