Why Slippage Happens

IntermediateNov 4, 2026 · 6 min read

Slippage happens when the price that clears your trade is no longer the price you planned from the quote. The book gets walked.

Key points

Slippage happens when the price that clears your trade is no longer the price you planned from the quote.
On a book, size can walk past the top ask; on a pool, your clip often is the move labeled price impact.
Absolute dollars mislead — check size against local depth where you need to trade right now.
Quote → sign → Pending → include is a waiting window; other flow can move the market before you land.
A wider max slippage does not add depth; on some public mempool swaps it can also leave room for a sandwich toward your max.

Short Answer

Slippage happens when the price that clears your trade is no longer the price you planned from the quote.

In plain English:

The book gets walked. The pool reprices under your size. The market moves while you wait. A thin route clears worse than the headline. On some public mempool swaps, other orders can sandwich yours and push the fill toward your max.

The Glossary definition — expected versus executed — is on What Is Slippage?. Keep that for the term. Use this Explainer when you need to name what moved.

The trading question

A mid, a last, or a best ask is a snapshot. It answers where a small clip could trade right now. It does not promise that your size clears there after you decide, sign, and settle.

After a bad ticket, ask:

Did the book walk, did the pool move, did time pass, was the path thin, or did surrounding orders sandwich me toward my max?

Different answers change the next clip. “The venue is slippery” does not.

Order-book walk

On a resting book, a marketable buy takes ask size level by level. The top price can be real and still not be your average fill.

Live scene: SOL/USDT, market buy about $5,000

You open SOL/USDT on a wallet-first order-book ladder. Chart last / mid looks “about 148.35.” The ask side (illustrative):

Ask price	Size at level	Rough USDT at that level
148.50	enough for ~$1,200	~1,200
148.80	enough for ~$1,800	~1,800
149.40	enough for ~$3,000	~3,000

You click Market Buy for about $5,000 USDT.

First ~$1,200 fills near 148.50
Next ~$1,800 walks to 148.80
Rest walks into 149.40
Average fill lands near 149.1 — not 148.35, and not even the best ask alone

That average-versus-plan gap is slippage from walking depth. Paying the ask instead of the mid is mostly spread. Walking deeper levels after the top is gone is why the fill keeps drifting.

Aha:

“Oh — the top ask was real. My size just outran it.”

How to read the ladder itself → What Is Depth of Market?.

Pool / curve impact

On an AMM, your size often is the move. As balances change — or as active liquidity in a range gets consumed — the executable price slides during the trade.

Live scene: swap quote, $200 vs $5,000

Open a pool-style SOL → USDT (or TOKEN → USDC) screen: amount field, quote line, Price impact, Max slippage.

Type about $200: impact might show near 0.05%; a 0.5–1% max slippage band feels fine.
Raise the same field to about $5,000: Price impact jumps — often into 1–3%+ on a thinner pool — and expected receive drops. If impact already sits near your max, the UI warns or the swap fails until you loosen the band.

Aha:

“Oh — my size moved the pool. Loosening max slippage doesn’t add depth.”

Screens label that move price impact. On pool routes, it is one of the main reasons the ticket no longer matches the first number you saw. Concentrated liquidity parks depth in ranges; it does not delete the mechanism. Engine background → What Is an AMM?.

Size versus local depth

Books and pools share one blunt check:

Against the size resting or active where I need to trade, is this clip still small — right now?

Absolute dollars mislead. A clip that is quiet on a deep major market can be loud on a thin alt book or a shallow pool. A clean mid with nothing behind it is how traders talk themselves into ugly averages.

How markets hold size under stress → What Is Liquidity?. For slippage: when size outruns local depth, the clearing price moves.

Waiting window

Even a fair engine needs a clock.

Quote → decide → submit → (on many on-chain paths) Pending → include. Other people keep trading in that window. The book or pool you priced against is not frozen.

Live scene: signed near 148.50, landed worse

You confirm in the wallet with max slippage at 1%. The UI sits on Pending. Congestion stretches the wait. When the receipt lands, average fill is worse than the signed quote — still inside 1%, so the trade did not revert. Nothing “broke.” Time opened a window for the market to move.

Failed or retried sends open another window and another chance for the same drift. Delay does not invent slippage by magic; it gives every other mechanism room to run.

Thin routes

A pair name is not always one deep puddle. Aggregated or multi-hop paths can print a neat headline while one hop is thin.

Live scene: TOKEN → WETH → USDC

Headline quote looks acceptable. Route detail shows the second hop is shallow. Same $5,000 notional; most impact sits on that hop. The top-of-screen pair never said “two puddles, one thin.”

If size looked reasonable and the fill still looks wrong, open the route breakdown before you blame the whole venue.

Amplifiers toward your max

On some public mempool-style swaps, your pending trade is visible before it lands. Other flow can place a buy ahead of you and a sell after you — a sandwich. That sequence can push the pool against you so your fill clears worse than the quote, often near the maximum slippage you still accepted.

Name it plainly:

Someone used the open band between your quote and your max. They did not invent a new market; they used the room you left.

This does not replace book walk, pool impact, delay, or thin routes. Most ugly tickets are still ordinary size-versus-depth. Sandwich / surrounding-order extraction is an amplifier: it widens a gap that was already open, and it only works up to the worst price your settings still allow.

Live scene: raise max slippage so the button stops failing

Impact already looks elevated. You move Max slippage from 1% to 5% so the swap stops failing. The receipt lands near that cap.

Two calm reads:

Ordinary impact may have needed most of that band.
If surrounding flow sandwiched the swap, the wider band also gave them more room to push toward.

Loosening max slippage did not add depth. It mainly authorized a worse landing — whether the shove came from your size alone or from orders around yours.

You do not need to assume every Pending swap is attacked. Read the ticket: if fill sits pinned near the max you set, ask whether ordinary impact explains it, or whether the path left a public window that other flow could use. How to tighten settings and routes lives on How to Manage Slippage and Execution Quality — this page only names the mechanism.

Worked scenes (quick read)

Scene	What moved
$5,000 market buy walks three asks	Book depth walk
Swap impact jumps from $200 → $5,000	Pool / curve impact
Pending inclusion, mid moved	Waiting window
Multi-hop with one thin pool	Route fragmentation
Fill pinned near raised max slippage	Sandwich / surrounding flow as amplifier (or ordinary impact using the same band)

You do not need every row every time. Name the one that matches the screen you used. Cutting size, splitting clips, tightening bounds, or changing routes are practice moves for later — this page stops at diagnosis.

Don’t Confuse With

Slippage = expected vs executed → What Is Slippage?
Spread = bid–ask gap for trading now → What Is Spread?
Liquidity = how much size sits near the touch under stress → What Is Liquidity?
Depth of market = the ladder of resting size → What Is Depth of Market?

Paying the ask instead of the mid is mostly spread. Walking deeper levels after that, or moving a pool with size, is why slippage shows up.

If you trade wallet-first — including on a venue such as edgeX — read impact, depth, pending time, route, and max slippage on the live screen before you sign. For the plain definition and the tolerance tradeoff, stay with What Is Slippage?.

Ready for the next step?

Continue to registration or trading from this page using the official links.

Start trading on edgeX

Disclaimer

This content is for educational purposes only and does not constitute investment advice. Trading digital assets and derivatives involves risk. Make sure you understand the products and consider your own circumstances before trading.

Explainers

Why Slippage Happens

IntermediateNov 4, 2026 · 6 min read

Slippage happens when the price that clears your trade is no longer the price you planned from the quote. The book gets walked.

Key points

Slippage happens when the price that clears your trade is no longer the price you planned from the quote.
On a book, size can walk past the top ask; on a pool, your clip often is the move labeled price impact.
Absolute dollars mislead — check size against local depth where you need to trade right now.
Quote → sign → Pending → include is a waiting window; other flow can move the market before you land.
A wider max slippage does not add depth; on some public mempool swaps it can also leave room for a sandwich toward your max.

Short Answer

Slippage happens when the price that clears your trade is no longer the price you planned from the quote.

In plain English:

The Glossary definition — expected versus executed — is on What Is Slippage?. Keep that for the term. Use this Explainer when you need to name what moved.

The trading question

A mid, a last, or a best ask is a snapshot. It answers where a small clip could trade right now. It does not promise that your size clears there after you decide, sign, and settle.

After a bad ticket, ask:

Did the book walk, did the pool move, did time pass, was the path thin, or did surrounding orders sandwich me toward my max?

Different answers change the next clip. “The venue is slippery” does not.

Order-book walk

On a resting book, a marketable buy takes ask size level by level. The top price can be real and still not be your average fill.

Live scene: SOL/USDT, market buy about $5,000

You open SOL/USDT on a wallet-first order-book ladder. Chart last / mid looks “about 148.35.” The ask side (illustrative):

Ask price	Size at level	Rough USDT at that level
148.50	enough for ~$1,200	~1,200
148.80	enough for ~$1,800	~1,800
149.40	enough for ~$3,000	~3,000

You click Market Buy for about $5,000 USDT.

First ~$1,200 fills near 148.50
Next ~$1,800 walks to 148.80
Rest walks into 149.40
Average fill lands near 149.1 — not 148.35, and not even the best ask alone

That average-versus-plan gap is slippage from walking depth. Paying the ask instead of the mid is mostly spread. Walking deeper levels after the top is gone is why the fill keeps drifting.

Aha:

“Oh — the top ask was real. My size just outran it.”

How to read the ladder itself → What Is Depth of Market?.

Pool / curve impact

On an AMM, your size often is the move. As balances change — or as active liquidity in a range gets consumed — the executable price slides during the trade.

Live scene: swap quote, $200 vs $5,000

Open a pool-style SOL → USDT (or TOKEN → USDC) screen: amount field, quote line, Price impact, Max slippage.

Type about $200: impact might show near 0.05%; a 0.5–1% max slippage band feels fine.
Raise the same field to about $5,000: Price impact jumps — often into 1–3%+ on a thinner pool — and expected receive drops. If impact already sits near your max, the UI warns or the swap fails until you loosen the band.

Aha:

“Oh — my size moved the pool. Loosening max slippage doesn’t add depth.”

Size versus local depth

Books and pools share one blunt check:

Against the size resting or active where I need to trade, is this clip still small — right now?

How markets hold size under stress → What Is Liquidity?. For slippage: when size outruns local depth, the clearing price moves.

Waiting window

Even a fair engine needs a clock.

Quote → decide → submit → (on many on-chain paths) Pending → include. Other people keep trading in that window. The book or pool you priced against is not frozen.

Live scene: signed near 148.50, landed worse

Failed or retried sends open another window and another chance for the same drift. Delay does not invent slippage by magic; it gives every other mechanism room to run.

Thin routes

A pair name is not always one deep puddle. Aggregated or multi-hop paths can print a neat headline while one hop is thin.

Live scene: TOKEN → WETH → USDC

Headline quote looks acceptable. Route detail shows the second hop is shallow. Same $5,000 notional; most impact sits on that hop. The top-of-screen pair never said “two puddles, one thin.”

If size looked reasonable and the fill still looks wrong, open the route breakdown before you blame the whole venue.

Amplifiers toward your max

Name it plainly:

Someone used the open band between your quote and your max. They did not invent a new market; they used the room you left.

Live scene: raise max slippage so the button stops failing

Impact already looks elevated. You move Max slippage from 1% to 5% so the swap stops failing. The receipt lands near that cap.

Two calm reads:

Ordinary impact may have needed most of that band.
If surrounding flow sandwiched the swap, the wider band also gave them more room to push toward.

Loosening max slippage did not add depth. It mainly authorized a worse landing — whether the shove came from your size alone or from orders around yours.

Worked scenes (quick read)

Scene	What moved
$5,000 market buy walks three asks	Book depth walk
Swap impact jumps from $200 → $5,000	Pool / curve impact
Pending inclusion, mid moved	Waiting window
Multi-hop with one thin pool	Route fragmentation
Fill pinned near raised max slippage	Sandwich / surrounding flow as amplifier (or ordinary impact using the same band)

Don’t Confuse With

Slippage = expected vs executed → What Is Slippage?
Spread = bid–ask gap for trading now → What Is Spread?
Liquidity = how much size sits near the touch under stress → What Is Liquidity?
Depth of market = the ladder of resting size → What Is Depth of Market?

Paying the ask instead of the mid is mostly spread. Walking deeper levels after that, or moving a pool with size, is why slippage shows up.

Ready for the next step?

Continue to registration or trading from this page using the official links.

Start trading on edgeX

Key points

Short Answer

The trading question

Order-book walk

Live scene: SOL/USDT, market buy about $5,000

Pool / curve impact

Live scene: swap quote, $200 vs $5,000

Size versus local depth

Waiting window

Live scene: signed near 148.50, landed worse

Thin routes

Live scene: TOKEN → WETH → USDC

Amplifiers toward your max

Live scene: raise max slippage so the button stops failing

Worked scenes (quick read)

Don’t Confuse With

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