The lowest fees in DeFi for trading between pegged-value assets.

Swap Basics

The Swap feature brings together a number of key pieces of the mStable infrastructure in a simple user interface. The resulting user experience is seamless swapping between any support pegged-value assets, including mUSD, mBTC, the underlying basket assets, and all Feeder Pool assets. Behind the scenes, the tool combines functions of minting and redeeming assets, swapping assets using the underlying liquidity pool, and the numerous Feeder Pools to allow a simple swap between any supported same-peg asset pair.

Using Swap

To swap between assets, simply navigate to the Swap tab on the mStable app. Select which category of pegged-value assets you would like to swap between (USD or BTC) and then select the assets that you which to exchange and the amount that you would like to trade.


The fees charged for any given swap will depend on the assets being exchanged due to the different mStable functionality that is used the facilitate trades.

The fees for each function are explained under the Swap Mechanics section below.

Swap Mechanics

To provide a seamless user experience, Swap makes use of a number of different mStable functions that can be chained together to allow trades between any supported same-peg assets. The different functions are described below.


Minting is the process of depositing supported pegged-value assets as collateral into a smart contract to create new mUSD or mBTC. For example, to mint mUSD, a user could deposit USDC, USDT, DAI, or sUSD.

Prices for minting and redeeming are set by a predetermined formula, known in the industry as a "bonding curve". When computing the prices, the formula takes weights of each underlying asset in the basket into account. Minting prices satisfy the law of demand, that is, the lower the weight of an asset in the basket, the higher the amount of mUSD or mBTC the user will receive in return. The price differentiation provided by the formula allows for arbitrage opportunities, and eventually for underlying asset prices, as computed by the formula, to track those of the market.

There are no fees charged to mint mUSD or mBTC so if a user is swapping one of the supported basket assets for mUSD or mBTC, there will be no fees charged on the swap.


Redeeming mUSD or mBTC is the process of exchanging the asset for one of the assets in the underlying pool.

The user selects which underlying asset they would like to receive in exchange for an equivalent amount of mUSD or mBTC, which is burned (ie. taken out of circulation). Again, the rate received will depend on the weight of the desired asset in the pool and will be determined by the bonding curve.

Users are charged a small fee when redeeming mStable assets. This fee is determined by MTA Governors and is currently set at 0.02% of the transaction value, charged in the asset received. This is among the lowest fees in DeFi.

Swapping assets within the main liquidity pools

Users can swap between assets within the main pools underlying mUSD or mBTC. To facilitate these swaps, mStable uses Stableswap, a bonding curve formula that is built specifically for trading pegged crypto assets, first implemented by Curve Finance. This allows efficient trading between assets and low slippage.

This is technically equivalent to minting mUSD or mBTC using one underlying asset and immediately redeeming to a different underlying asset. The fee charged is equivalent to the swap fee set by MTA Governors, currently 0.02%.

Feeder Pools

As described in the Pools section, Feeder Pools allow swaps between other supported assets that share the same peg as the desired mStable asset. The Swap interface makes use of these pools to allow trades using any feeder asset.

For swaps between feeder assets and assets in the main pools or vice versa, the asset will be converted into mUSD or mBTC first and then into the desired asset.

There are no fees on swaps into mUSD or mBTC using the Feeder Pools, and a small charged when swapping into the feeder asset.

Swap Benefits

mStable's Swap provides some of the most affordable and efficient swaps in DeFi on pegged-value assets.

mStable is integrated with major DEX aggregators to allow them to take advantage of these benefits.

Arbitrage opportunities can also arise within the mStable pools when a spread exists between asset prices. When the price differential is greater than the cost of the swap fee plus gas, arbitrageurs will take advantage of this, generating swap fees and helping to balance the weights of assets in the liquidity pools.

Fees generated through Swap are feed back to users holding deposits in the Save contracts or Feeder Pool liquidity providers.

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