Reference
Understanding Liquidity
Depth, slippage, and price impact — why a $1M trade in one pool is free and ruinous in another.
TradFi →Order-book depth & market impact
01 · Concept — what problem does it solve?
Liquidity is the answer to a single question: how much can you trade before the price moves against you? A deep market absorbs size with little movement; a thin one lurches on the first decent order. Everything downstream in DeFi — a swap quote, a , an , a peg — ultimately rests on whether there is enough liquidity at the right price when it is needed.
"TVL" (total value locked) is the headline number, but TVL across a wide price range is shallow where it matters. What you actually care about is depth near the current price.
02 · Mechanics
- Depth: how much capital sits within X% of the mid-price. Deep books/pools quote tight; thin ones gap.
- Price impact: the move your own trade causes by walking up the curve. Grows with trade size relative to reserves — it is the 's version of a spread.
- : the gap between the quoted price and the executed price — price impact plus any adverse move between signing and inclusion. Your slippage tolerance is also a sandwich attacker's budget.
- Provision shape matters: Uniswap v2 spreads liquidity across all prices (shallow everywhere); Uniswap v3 concentrates it; Curve flattens the curve for pegged assets so depth pools near parity.
- Mercenary vs. sticky liquidity: emissions rent depth that leaves when rewards stop; fees and make it stay.
03 · Formulas
// constant-product price impact for buying Δx of token X
exec_price = y / (x − Δx) // worse than spot y/x
impact = exec_price / (y/x) − 1
// rule of thumb: in an x·y=k pool, trading p% of a reserve
// moves price ≈ p% (small trades) and far more as p grows
// slippage tolerance caps the worst fill you will accept
min_out = quote · (1 − tolerance)
04 · Edge cases & risks
- TVL ≠ usable depth — a pool can show huge TVL but be shallow at the current price (wide v3 ranges, idle capital); always look at depth, not the headline.
- Liquidity is reflexive — it evaporates exactly when you need it. In a crash, LPs withdraw and arbitrageurs widen, so the depth that priced your risk yesterday is gone today.
- Fragmentation — the same pair split across chains, versions, and fee tiers means no single venue is deep; aggregators exist to stitch it back together. See DEX aggregators.
- Providing liquidity is not passive income — LPs are short volatility and lose to informed flow. See Impermanent Loss.
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