Slippage Rate Protection
You are referring to the Legacy
version of KyberSwap docs.
For the most updated information, please refer to:
Classic
Safeguarding Users From Slippage Rates
The token conversion rate varies with different source token quantities. It is important to highlight the slippage in rates to the user when dealing with large token amounts. We list some methods on how this can be done below.
Method 1: Reject the transaction if the slippage rate exceeds a defined percentage
Call
getExpectedRate
for 1 ETH equivalent worth ofsrcToken
.Call
getExpectedRate
for actualsrcToken
amount.If the obtained rates differ by a defined percentage (either in the smart contract, or as a user input), reject the transaction.
Method 2: Display rate slippage in the user interface
An example of how this could be done is shown above. How the rate slippage is calculated is as follows:
Call
getExpectedRate
for 1 ETH equivalent worth ofsrcToken
.Call
getExpectedRate
for actualsrcToken
amount.Calculate the rate difference and display it prominently in the user interface.
Slippage rates when using maxDestAmount
maxDestAmount
In the case where maxDestAmount
is being used, beware of slippage rates when maxDestAmount
is significantly lower than srcQty
. We give an example below.
Users wants to swap for a
maxDestAmount
of 3000 DAI, but specifies asrcQty
of 300 ETH.Kyber will search the best rate for the
srcQty
of 200 ETH, but the rate might be significantly worse than rates for lowersrcQty
. For example, the user gets a rate of 1 ETH = 100 DAI, while he could have gotten a better rate of 1 ETH = 200 DAI if he specified a lowersrcQty
.Kyber will use the rate to calculate the amount necessary for 2900 DAI, and refund the rest of the unused ETH back to the user. In the case mentioned above, 30 ETH will be used, and the remaining 270 ETH returned to him. He could have instead needed just half that amount (15 ETH) had he specified a lower
srcQty
instead.
In summary, if srcQty
is significantly larger than maxDestAmount
, the user could potentially be forced to trade with significantly worse rates.
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