Algorithmic Market Operations (AMO)

Algorithmic market operations (AMOs) are smart contracts that automatically manage a stablecoin's collateral and supply in order to keep it at its target value, usually one US dollar. Each AMO follows a set strategy, such as adding liquidity to a trading pool or lending reserves to a protocol, and can create or retire stablecoins as long as doing so does not threaten the peg. The design was introduced by Frax Finance in 2021 as part of the second version of its protocol.

The name deliberately echoes central bank open market operations, in which a central bank buys or sells assets to steer interest rates and money supply. AMOs apply a similar idea through code on public blockchains. They sit between purely algorithmic stablecoins and fully collateralized stablecoins, using reserves actively rather than leaving them idle.

Picture a currency exchange booth that promises to always swap one token for one dollar. Most of the time, many of the dollars in its safe just sit there. An AMO is like a set of strict instructions telling the booth's manager what they may do with those idle dollars: lend some out safely, keep some ready in the busiest marketplaces, and pull everything back the moment the promise of one-for-one looks at risk.

Because the instructions are written in code and visible to everyone, anyone can check what the booth is doing with its money. The booth earns income on its reserves, and the token stays near a dollar, as long as the instructions and the markets behave as expected.

In the Frax design, each AMO is a module with permission to mint and redeem the protocol's stablecoin within rules set by governance. A useful way to understand an AMO is through four questions the design asks:

• Decrease collateral ratio. Can it expand stablecoin supply without weakening backing beyond safe limits?
• Market operations. What does it do with funds while the peg is steady?
• Increase collateral ratio. How does it shrink supply or add backing if the peg comes under pressure?
• Profit. How does it earn revenue for the protocol?

If the stablecoin trades above $1, an AMO can mint more and deploy it, pushing the price down; if it trades below $1, AMOs withdraw funds and buy back or retire stablecoins.

• Liquidity AMOs. Supply stablecoins and reserves to liquidity pools on automated market makers, especially pools on Curve, deepening markets so the peg holds under large trades.
• Lending AMOs. Mint stablecoins directly into lending markets, where they are borrowed against collateral, earning interest for the protocol.
• Investor AMOs. Place idle reserves into yield-bearing strategies.
• Concentrated liquidity AMOs. Provide liquidity in narrow price ranges on exchanges that support them.

Frax launched in December 2020 as a "fractional-algorithmic" stablecoin, partly backed by collateral and partly by its governance token. AMOs, added in 2021, helped Frax grow quickly, especially through deep Curve pools. The May 2022 collapse of TerraUSD, an unbacked algorithmic stablecoin that entered a death spiral, led many users to distrust partly algorithmic designs. After the USDC depeg of March 2023, Frax governance voted to move towards full collateralization. In 2025 the project renamed its dollar stablecoin frxUSD and its governance token FRAX, while keeping AMO-style modules as part of its reserve management.

AMOs make reserves work harder, but they also expose them to more risk. Funds placed in lending markets or liquidity pools depend on the security of those protocols, so a hack or failure elsewhere can reduce backing. Stablecoins minted into lending markets are only as good as the collateral of the borrowers. Critics argue that AMOs can blur how much of a stablecoin's supply is truly backed by independent assets versus by the protocol's own tokens. Governance decisions about which AMOs to approve concentrate power in token holders, who may favour growth over safety. Like all stablecoin designs, AMO-based systems can lose their peg in severe market stress.

• Frax