Market cap is not liquidity
Lesson 2 · about 8 min
Every crypto ranking site sorts coins by market capitalisation. Every beginner reads that number as "how much money is in this coin". It is not, and the gap between what market cap says and what you can actually sell is where alt traders get hurt.
What market cap measures
Market cap = circulating supply × last traded price.
That is all. If a token has 1 billion units in circulation and the last trade printed at $0.50, the site shows a $500 million market cap. Nobody paid $500 million. Possibly nobody has paid more than a few thousand dollars in total. The number is a multiplication, not a bank balance.
Two things make it worse in crypto than in stocks:
- Circulating supply is self-reported or estimated. Many projects hold most of their tokens in team, foundation or investor wallets that are technically unlocked but never sold. The "circulating" figure may be wrong in either direction.
- The last price can be set by a tiny trade. On a thin market, one $200 buy can lift the price 5% and add $25 million of "market cap" to a $500 million token.
What liquidity measures
Liquidity is how much you can buy or sell, right now, without moving the price against yourself. It lives in the order book (Module 3), not in the market cap.
Practical measures you can check in a minute:
- Spread. The gap between the best bid and best ask as a percentage of price. BTC on a major exchange: a few hundredths of a percent. A mid-tier alt: 0.2% to 1%. A microcap: 3% or more.
- Depth at 2%. Total dollars resting on the bids within 2% below the price (and on the asks within 2% above). This is how much you could sell before pushing the price down 2%. Most ranking sites show this figure for each exchange.
- Real volume. Daily traded value on exchanges you trust, not the aggregate headline figure (which Lesson 4 explains is often inflated).
A worked comparison
Two tokens, both showing a $300 million market cap:
| Token | Spread | Depth at 2% (bids) | Trusted daily volume |
|---|---|---|---|
| A | 0.10% | $1,200,000 | $40,000,000 |
| B | 1.50% | $18,000 | $600,000 |
Suppose you hold $30,000 of each and want out today.
Token A: your sale is 2.5% of the 2% depth. You will fill inside the spread with minimal slippage. Cost of exit: roughly $30 to $60.
Token B: your sale is 167% of the 2% depth. You will eat every bid within 2%, then keep going. Realistically you would move the price 5% to 10% and pay $1,500 to $3,000 to exit, or split the sale over several days and hope the price holds. Same market cap, entirely different asset.
Key idea: Market cap tells you what the last buyer paid multiplied by the supply. Liquidity tells you what the next buyer will pay for your size. Only the second one is money.
Fully diluted value
You will also see "FDV" (fully diluted value): total eventual supply × price. When FDV is many times the market cap, a large amount of supply is still locked and will be released over time, usually to insiders who paid far less than you. Module 5 shows how to read the release schedule. For now, treat a big gap between market cap and FDV as a warning sign, not a detail.
Why this decides your position size
The risk management course sizes positions from the stop distance. In crypto you must add a second cap: never hold a position larger than a small fraction of the depth you can actually sell into. A reasonable beginner rule is to keep any single alt position below 5% of the 2% bid depth on your exchange. If that makes the trade too small to matter, that is the market telling you it is too thin for you.
Try it: Pick three coins ranked 10th, 100th and 300th by market cap. For each, find the spread and the 2% depth on the largest exchange listing it. Compute how many dollars you could sell before moving the price 2%. Write down whether your normal position size would fit.
Recap
- Market cap = circulating supply × last price. It is a multiplication, not money in the coin.
- Liquidity is measured by spread, depth at 2%, and trusted volume. Check all three.
- Two tokens with the same market cap can cost 50 times more or less to exit.
- A big gap between market cap and fully diluted value means locked supply is coming.
- Cap alt positions by depth, not just by stop distance.
See it drawn
Original diagrams for the ideas on this page. Illustrative, not real market data.