Frax
Frax Finance
Market cap (static): ~$670M
Overview
Pioneer hybrid stablecoin combining fractional fiat collateral with algorithmic mechanisms. The protocol evolved through v1 (algorithmic), v2 (AMO-based), into a full DeFi suite including Fraxswap (TWAMM) and Fraxlend. FXS token governs the system.
Features
Engineering-oriented breakdown of capabilities: standards, who they matter for, integration rationale, per-feature risks, and vetted external references (specs, docs, verified source).
| Feature | Standards | Audience | Why it matters | Risk / caveat | References |
|---|---|---|---|---|---|
Fractional reserve model stability | — | Both | FRAX supply splits between collateral and FXS — integrations must read live CR and redemption mechanics. | CR changes with market conditions; redemption mix shifts between USDC and FXS. | |
Algorithmic Market Operations — AMO stability | — | Both | Protocol deploys idle collateral to strategies — affects balance sheet and tail risk beyond vanilla ERC-20 transfer. | Strategy failure or exploit in AMO modules can impact backing perception. | |
Fraxswap TWAMM stability | — | User | Native AMM with TWAMM order type — relevant for routing and MEV-aware trading integrations. | AMM smart contract risk separate from FRAX token contract. | |
Fraxlend isolated pairs yield | — | User | Isolated lending markets — each pair has unique oracle and liquidation params. | Liquidation and interest rate spikes per pair; not a single global lending risk model. | |
sFRAX ERC-4626 vault yield | User | Yield-bearing FRAX position — integrate as standard vault with Frax-specific withdrawal rules. | Vault parameters and underlying AMO yield can change; smart contract risk. | ||
FXS governance token governance | — | Both | FXS votes control parameters — integrations may need to monitor governance for economic changes affecting FRAX. | Token price and governance attacks are systemic to hybrid model. |
EIP / ERC support matrix
Standards support for FRAX. Click an EIP to jump to the global deep-dive section.
| Standard | Status | Notes |
|---|---|---|
| ERC-20 Fungible token standard | Implemented | DEX and lending treat FRAX as ERC-20; supply shocks follow collateral ratio and AMO policy. |
| EIP-712 Typed structured data signing | Not implemented | No native typed-data signing surface on the FRAX ERC-20. |
| EIP-2612 Permit — gasless ERC-20 approval | Not implemented | Gasless approval flows require Permit2 or bespoke meta-tx wrappers. |
| EIP-3009 transferWithAuthorization | Not implemented | Payment relayers cannot use USDC-style authorizations on FRAX directly. |
| EIP-1967 Standard proxy storage slots | Implemented | Correct ABI attachment depends on reading proxy → implementation relationship per chain. |
| EIP-1822 UUPS — universal upgradeable proxy | Not implemented | Low for typical FRAX holders. |
| ERC-4626 Tokenized yield vault standard | Implemented | Composable with ERC-4626 routers, aggregators, and money markets that auto-detect the interface. |
| EIP-1271 Signature validation for smart contracts | Not implemented | Smart wallets follow standard ERC-20 approval paths. |
Technical notes
FRAX uses TransparentUpgradeableProxy. Core contracts — FraxPool.sol (mint/redeem with CR check), FXS ERC-20 (burned proportionally on FRAX redemption), UniswapPairOracle (TWAP price feeds), FraxAMOMinter.sol (coordinates AMO strategy deployments). Mint: deposit USDC (CR%) + burn FXS ((1-CR)%). Redeem: return FRAX, receive USDC + FXS at current CR. AMOs extend idle collateral into external yield strategies without increasing FRAX supply or breaking peg.
Reserves & peg
- Reserves
- USDC (collateral portion) plus protocol-owned FXS
- Collateral
- Hybrid — USDC + FXS
- Peg mechanism
- Algorithmic via CR adjustment and redemption arbitrage
- Auditor
- Trail of Bits, Certik
Ecosystem
- DeFi integration
- Fraxswap, Fraxlend (native); Curve frax3crv gauge; Convex
- Yield
- sFRAX variable via AMO revenues
Risk factors
Networks & contracts
Deployments by chain — primary rows are highlighted. Always verify addresses against issuer docs before mainnet integrations.
| Network | Standard | Contract | Explorer |
|---|---|---|---|
EthereumPrimary | ERC-20 | 0x853d955aCEf822Db058eb8505911ED77F175b99e | View |
ArbitrumSecondary | ERC-20 | 0x17FC002b466eEc40DaE837Fc4bE5c67993ddBd6F | View |
OptimismSecondary | ERC-20 | 0x2E3D870790dC77A83DD1d18184Acc7439A53f475 | View |
PolygonSecondary | ERC-20 | 0x45c32fA6DF82ead1e2EF74d17b76547EDdFaFF89 | View |
AvalancheSecondary | ERC-20 | 0xD24C2Ad096400B6FBcd2ad8B24E7acBc21A1da64 | View |
BNB ChainSecondary | BEP-20 | 0x90C97F71E18723b0Cf0dfa30ee176Ab653E89F40 | View |
Engineering deep dive
Integration notes
FRAX’s collateral ratio and AMO positions change system behaviour over time—do not hard-code assumptions from a single snapshot. FXS exposure is part of the economic model for redemptions and governance.
Native stack
Fraxswap / Fraxlend are purpose-built around FRAX—use their docs for composable integrations.