Frax Ether Integration (Liquid Staking)
Frax Ether — part of Frax Finance ecosystem, includes two tokens: frxETH (liquid staking token) and sfrxETH (staking version). Specificity: frxETH itself doesn't accrue rewards — need to stake it in sfrxETH for yield. Interesting mechanic for DeFi.
Two-Token System
frxETH: 1:1 peg with ETH. Doesn't provide yield itself. Used as liquid ETH-equivalent in DeFi (Curve pools, AMM).
sfrxETH: staked frxETH. ERC-4626 vault. All ETH staking yield accumulates in sfrxETH — its exchange rate grows. frxETH used in DeFi LP pools doesn't receive staking yield, so all yield concentrated in sfrxETH holders. Makes sfrxETH one of highest-yielding LST.
Mint frxETH
interface IfrxETHMinter {
function submit() external payable;
function submitAndDeposit(address recipient) external payable returns (uint256 shares);
}
// Mint frxETH
IfrxETHMinter(FRXETH_MINTER).submit{value: ethAmount}();
// Mint and immediately deposit into sfrxETH vault
uint256 sfrxETHAmount = IfrxETHMinter(FRXETH_MINTER).submitAndDeposit{value: ethAmount}(recipient);
sfrxETH Vault (ERC-4626)
interface IsfrxETH {
function deposit(uint256 assets, address receiver) external returns (uint256 shares);
function withdraw(uint256 assets, address receiver, address owner) external returns (uint256 shares);
function redeem(uint256 shares, address receiver, address owner) external returns (uint256 assets);
function convertToShares(uint256 assets) external view returns (uint256 shares);
function convertToAssets(uint256 shares) external view returns (uint256 assets);
function syncRewards() external;
}
// frxETH → sfrxETH
IERC20(frxETH).approve(address(sfrxETH), frxETHAmount);
uint256 sfrxETHShares = IsfrxETH(SFRXETH_ADDRESS).deposit(frxETHAmount, recipient);
DeFi Strategies with frxETH
Curve frxETH/ETH pool: add frxETH for CRV/CVX rewards instead of staking yield.
Leveraged staking: deposit ETH → get sfrxETH → use as collateral in Aave → borrow ETH → deposit again.
Integration of Frax Ether — 1-2 weeks. ERC-4626 sfrxETH significantly simplifies integration.