frxUSD (formerly FRAX) is the fully collateralized, fiat mint-redeemable stablecoin of the Frax Finance Protocol. It is designed to be pegged to the US dollar. ^[4]

Overview

frxUSD is the stablecoin of the Frax Finance Protocol. The frxUSD stablecoin is designed to be pegged to the US dollar. frxUSD is the first and only stablecoin with parts of its supply backed by collateral and part of the supply fractionally stabilized. ^[1] On February 23rd, 2023, the Frax Finance community voted to fully collateralize the protocol’s native stablecoin frxUSD (formerly FRAX).

The price of frxUSD and collateral are all calculated with a time-weighted average of the Uniswap pair price and the ETH:USD Chainlink oracle. The Chainlink oracle allows the protocol to get the true price of USD instead of an average of stablecoin pools on Uniswap.

Historically, at genesis, frxUSD (formerly FRAX) was 100% collateralized, meaning that minting frxUSD only requires placing collateral into the minting contract. During the fractional phase, minting frxUSD required placing the appropriate ratio of collateral and burning the ratio of FRAX (formerly FXS). The protocol is designed to accept any type of cryptocurrency as collateral and this implementation of the Frax Protocol mainly accepted on-chain stablecoins as collateral to smoothen out volatility in the collateral in order for frxUSD to transition to more algorithmic ratios smoothly. This design was implemented so that as the velocity of the system increases, it becomes easier and safer to include volatile cryptocurrencies such as ETH and wrapped BTC into future pools with governance.

Price Stability

frxUSD remains pegged to the US dollar due to the Algorithmic Market Operations Controller (AMO), a framework for composable, autonomous central banking legos.

An AMO module is an autonomous contract(s) that enacts arbitrary monetary policy so long as it does not change the FRAX price off its peg.

AMO controllers can perform open market operations algorithmically but cannot arbitrarily mint FRAX out of thin air and break the peg. The AMO controllers allow for keeping Fraxe’s base layer stability mechanism pure and untouched.

Properties of each AMO:

• Decollateralize - the portion of the strategy that lowers the CR.
• Market operations - the portion of the strategy that is run in equilibrium and doesn't change the CR.
• Recollateralize - the portion of the strategy that increases the CR.

Frax Staking

Frax Finance protocol allows frxUSD holders to lock up frxUSD tokens to generate yield on various pools on different chains. ^[2]

Full Collateralization

The Frax Finance community voted to Fully Collateralize its native stablecoin frxUSD (formerly FRAX) on February 23, 2023, as per snapshot FIP-188. ^[3] The details and motivations are as follows:

The time has come for Frax to gradually remove the algorithmic backing of the protocol. The Frax protocol has grown and evolved dramatically since the protocol launched in December 2020. The original protocol included a variable collateral ratio which adjusted based on the market demand of FRAX, effectively letting the market dictate how much collateral was necessary for each FRAX to equal $1.00. This was a highly innovative, elegant approach that Frax pioneered but has now outgrown. The costs of being slightly undercollateralized now far outweigh the benefits – especially because it can undermine the perceived safety of FRAX. Gradually shifting the protocol to 100% CR is the best path forward for the long-term health and growth of the protocol. This is a significant change to the protocol that over time effectively retires the algorithmic backing of Frax. It has become clear to many active in the community that this is the best path forward. The intention of this proposal is to coordinate the community on increasing the CR to 100% permanently. It is more focused on the destination (100% CR) than how we get there - there is no imminent need to increase the CR and there are many ways of reaching the target CR. Ideally growth, asset appreciation and protocol earnings will increase the CR to 100% over time. To be clear, this proposal does not rely on minting any FXS to achieve the 100% CR.

Motivation

Frax has always approached the algorithmic backing of FRAX conservatively. Even before launch, it was clear that relying on FXS to back the algorithmic portion of FRAX required locked liquidity to ensure smooth functioning of the protocol. Unfortunately, we have now seen many projects that didn’t understand this and failed. The downside of locked liquidity is that the protocol pays for it in the form of FXS rewards. While this approach made sense to start, the circumstances around Frax have changed. Frax achieved 0 to 1 product market fit and now has a supply exceeding 1,000,000,000 FRAX. The next phase of growth requires increasing the “money” attributes of FRAX, specifically making FRAX an asset that users are comfortable holding, without any incentive, as a long-term store of value. The small algorithmic backing of FRAX creates the perception that FRAX is the less safe option for users to hold, especially after UST’s failure tainted the algorithmic stablecoin concept (whether fairly or unfairly). There is very little benefit in maintaining the current CR of 92%. @dennett has made the point that FRAX can be fully collateralized by non-FXS assets and still be fractional reserve by deploying protocol owned liquidity via AMOs. Increasing protocol collateral also means that additional collateral can be deployed via AMOs to create liquidity and revenue for the protocol. Frax will continue to be the most capital efficient safe stablecoin while removing the need to constantly fund locked liquidity. At this point, all protocol expansions occur via AMO and effectively are at 100% CR. This means that protocol growth increases the CR. The gentlest way to increase the CR is to retain protocol earnings as the protocol grows. As part of this proposal, FXS buybacks will be deferred until the CR reaches 100%. This is effectively an investment in the future of Frax that will increase protocol assets and remove the need for FXS emissions towards locked liquidity. There appears to be little impact from FXS buybacks lately and the impact is probably overestimated at this point. This proposal does not impact the current veFXS yield. From the perspective of FXS holders, this proposal should increase the soundness / perception of Frax and accelerate protocol growth. Finally, this proposal would authorize protocol comptrollers to strategically exchange up to $3m of protocol assets for frxETH each month. frxETH is becoming an important decentralized asset on Frax’s balance sheet, both increasing the CR while also increasing the supply of frxETH and validators. frxETH also offers a strong return potential for the protocol. Up to $3m per month is a small amount given the size of Frax’s protocol assets – it also limits the protocol’s exposure to frxETH price volatility by keeping the value relatively small. The selling of protocol assets authorized by this proposal is not intended to decrease Frax’s holdings of CVX or CRV and will not include either asset. ^[1]