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Why a stablecoin swap can still go wrong

USDT to USDC should cost almost nothing. When it does not — depegs, wrong-chain versions, shallow pools — and how to check before you trade.

By FBT Swap · 5 October 2026

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        Pool fee
        Hundredths of a percent on dedicated stable curves
      
        Main risk
        Holding a bridged version with its own shallow pool
      
        Second risk
        Trading into a stable curve while a peg is moving

FBT Swap

What you should know

Swapping one dollar stablecoin for another is the cheapest trade in crypto when it works. Specialised pools price them at a tiny fee because neither side is expected to move.

The failures are therefore not about fees. They are about which version of the token you hold, and whether the peg is holding at that moment.

Why the fee is so low

Stable-to-stable pools use a curve designed for assets that trade near parity, giving very deep effective liquidity around 1:1 and a fee tier measured in hundredths of a percent. Price impact stays negligible for sizes that would move a normal pool.

That holds while both assets are near their peg. It stops holding the moment one is not.

The wrong-version problem

There are multiple tokens called USDC on several chains: a native issuance and one or more bridged versions. They are different contracts with different liquidity and different redemption rights, and a pool for one is not a pool for the other.

Checking the contract address, not the symbol, is the whole defence. The networks guide covers native versus bridged in detail.

When a peg slips

During a depeg the specialised curve works against you: it is built to assume parity, so it offers a lot of liquidity at prices that are no longer fair. Trading into it while the price is moving can execute far from where you expected.

This is the one case where a stablecoin swap deserves the same care as a volatile pair — check the live rate, not the assumption.

Practical checks

Confirm the contract address of both tokens. Check the quoted rate is close to 1:1 and look at the price impact figure rather than assuming it is zero. On an expensive network, remember fixed gas can still exceed the entire fee.

FBT Swap shows rate, impact and the 0.70% platform fee before you sign, which makes an off-parity quote immediately visible instead of surprising.

At a glance

Pool fee

Hundredths of a percent on dedicated stable curves

Main risk

Holding a bridged version with its own shallow pool

Second risk

Trading into a stable curve while a peg is moving

Check

Contract address, live rate and price impact — never the symbol alone

FAQ

Frequently asked questions

Clear answers before you decide.

Are all stablecoins equally safe?

No. Backing, redemption rights, issuer jurisdiction and transparency differ substantially between them, and an algorithmic stablecoin is a different risk class entirely from a fully reserved one.

Why did my USDC swap have high price impact?

Most likely you hold a bridged version whose pool is far shallower than the native one, or the pair you selected routes through a volatile intermediate. Check the contract address first.

Is it worth swapping stables to save on fees?

Only if the destination pool is meaningfully deeper for your next trade. On a cheap network it can be; on an expensive one the gas for two transactions usually erases the gain.

Risk notice

Crypto assets are volatile and on-chain transactions cannot be reversed. You can lose money, including all of it. Nothing here is financial advice.