f(x) USD Saving

CoinGecko’s fx-usd-saving is 0x7743e50F534a7f9F1791DdE7dCD89F7783Eefc39, not fxUSD. It began as a TransparentUpgradeableProxy on 2025-03-17. At review it showed 65,023,994.453686079836564869 shares across 382 holder addresses and delegated to 0xE4031e271809d20074E4bef1caeEfEc5f710e8A6.

The share’s ERC-4626 asset is 0x65C9A641afCEB9C0E6034e558A319488FA0FA3be. That fxSP base pool holds the protocol’s fxUSD/USDC Stability Pool position. fxSAVE is therefore two layers away from the collateral that ultimately supports fxUSD.

The exchange rate grows when reinvested rewards increase assets per share. It is not a rebasing balance, bank interest or fixed coupon. A falling base-pool NAV can also pull the share value down.

This extra wrapper also changes accounting language: holders measure shares, while the pool measures fxSP assets and the stablecoin system measures collateral NAV. Confusing those three units can make an apparent yield or loss look larger than it is.

When fxUSD trades below its threshold, the Stability Pool spends USDC to buy it; above one dollar, it sells fxUSD for USDC. Depositors supply inventory for this peg arbitrage.

Income arrives from collateral yield, trading and funding fees, unused slippage, Aave positions and reward emissions. Governance decides distributions among Stability Pool, leveraged positions, treasury and veFXN.

A keeper triggers harvest. The contract removes a bounty and expense share, hands rewards to a harvester for conversion, and restakes the resulting base assets. “Automatic” still depends on callable code, liquid conversion routes and privileged addresses.

The patient path burns fxSAVE and moves corresponding 0x65C9A641afCEB9C0E6034e558A319488FA0FA3be into a deterministic LockedFxSaveProxy owned operationally by the fxSAVE contract. It requests the base-pool unlock; after the published 60-minute period the user calls claim for fxUSD and USDC.

The router offers an atomic route that burns shares and converts components to a chosen output. Documentation says this fast route charges a withdrawal/redemption fee and uses min-out protections, so its result depends on liquidity and slippage. The published Stability Pool cooldown is 60 minutes. The Fees page lists a 1% early-exit fee; the separate 0.5% redemption entry is under pegging risk parameters and is not established as the fxSAVE exit fee. These are adjustable documented settings, not a fresh live quote.

The delay prevents a user from entering or leaving against stale pool composition at everyone else’s expense. It is a risk control, but during depeg or congestion it also traps the user in the pool for that interval.

SavingFxUSD gives DEFAULT_ADMIN_ROLE the power to change treasury, harvester, expense ratio, bounty ratio and batching threshold, and to grant a role that claims for another account. The TransparentUpgradeableProxy admin can change implementation 0xE4031e271809d20074E4bef1caeEfEc5f710e8A6. A CLAIM_FOR_ROLE holder can claim another account’s unlocked assets to a receiver it chooses; claimFor does not require the affected depositor’s signature. This affects pending withdrawals even though ordinary share transfers lack a blacklist. Current holders of this role were not independently established.

The share code does not pause or blacklist ordinary transfers. That fact should not be stretched to the full system: new USDC deposits into the base pool can stop when its oracle price reaches 0.995 or below, routers choose conversions, gauges and Convex-style vaults custody positions, and governance can adjust fees.

The published community multisig lists nine signers, but the reviewed sources did not establish which threshold, delay and current accounts hold every fxSAVE admin or proxy-admin role. Holders do not gain those powers by owning the share.

The f(x) invariant allocates collateral value between low-volatility fxUSD and leveraged xPOSITION/sPOSITION claims. Rebalancing begins at 88% LTV and hard liquidation at 95% in the published global parameters.

If rebalancing and liquidation leave bad debt, a reserve fund is the first buffer; documentation says remaining bad debt is redistributed among leveraged positions. Even so, fxSAVE relies on fxUSD’s peg and on USDC, and its pool actively changes composition during stress.

No official source reviewed identifies fxSAVE as an obligation of a legal issuer or an insured deposit. The enforceable mechanics we can see are contract shares, withdrawal calls and governance-controlled parameters. “Saving” is a product label, not a statutory protection.