Stability Fee

What Is a Stability Fee?

A stability fee is a variable interest rate that DeFi lending protocols charge borrowers who mint stablecoins against locked collateral. The term originates from MakerDAO (now rebranded to Sky Protocol), where users deposit crypto assets like ETH or WBTC into vaults and generate DAI stablecoins. The stability fee represents the cost of maintaining that debt position over time.

Think of it as the DeFi equivalent of a bank loan interest rate, but with a key difference: the rate is set by governance token holders through on-chain voting rather than by a central bank or credit committee. Each collateral type can have its own independently governed stability fee, reflecting the specific risk profile of that asset.

The stability fee serves a dual purpose. It generates revenue for the protocol, and it functions as a monetary policy lever to keep the stablecoin trading at its target peg. When DAI drifts below $1, governance can raise the stability fee to discourage new minting and reduce supply. When DAI trades above $1, lowering the fee encourages more borrowing and increases circulating supply.

How It Works

The stability fee accrues on vault debt continuously, compounded every second on-chain. Here is the lifecycle of a vault position and how the fee applies:

1. A user deposits collateral (ETH, WBTC, or other approved assets) into a Maker/Sky vault, meeting the required overcollateralization ratio (for example, 150% for ETH-A vaults)
2. The user mints DAI or USDS against that collateral, up to the maximum allowed by the collateral ratio
3. The stability fee begins accruing immediately on the outstanding debt balance, compounding every second
4. When the user repays their debt to close or reduce the vault position, they must return the borrowed DAI plus all accumulated stability fees
5. Collected fees flow into the protocol's Surplus Buffer, funding operations and eventual MKR/SKY token buybacks

Per-Second Compounding

Unlike traditional loans that compound monthly or annually, stability fees compound every Ethereum block (roughly every 12 seconds). The protocol's Jug smart contract module stores annual rates as per-second accumulator values using ray-precision arithmetic (27 decimal places).

For example, a 2% annual stability fee translates to a per-second rate of approximately 1.0000000006279371924910298109948. The smart contract multiplies this factor by the outstanding debt each time the rate is "dripped" (updated):

// Simplified rate accumulation logic from the Jug contract
// rate: per-second compounding factor (ray precision)
// debt: outstanding vault debt

accumulated_rate = accumulated_rate * rate^(now - last_drip_time)
total_owed = principal * accumulated_rate

This mechanism means a vault owner who borrows 10,000 DAI at a 5% annual stability fee would owe approximately 10,500 DAI after one year, with the fee growing slightly faster than simple interest due to continuous compounding.

Per-Collateral Rates

Each collateral type (called an "ilk" in Maker terminology) carries its own stability fee rate. Riskier collateral types typically have higher fees. For context, the December 2024 out-of-schedule governance vote set the following rates:

Higher-risk vault types (lower collateral ratios like ETH-B at 130%) command higher stability fees to compensate the protocol for increased liquidation risk. WBTC vaults carry a premium reflecting additional custody and trust assumptions beyond the underlying asset's volatility.

Governance and Rate Setting

Stability fee rates are set through a two-stage DAO governance process. Unlike algorithmic rate models (such as those used in Aave or Compound), Maker/Sky rates are explicit policy decisions made by token holders:

1. Governance Poll: MKR or SKY token holders vote on proposed rate changes in an off-chain signaling poll lasting 2 to 3 days, establishing community consensus
2. Executive Vote: the winning option is bundled into an on-chain executive vote, where token holders lock their tokens to cast binding votes
3. Governance Security Module (GSM): after passing, a mandatory delay (typically 16 to 48 hours) provides a security window before changes take effect on-chain

Rate proposals are authored by risk teams who analyze market conditions, collateral risk profiles, and peg behavior. Changes typically move in increments of 25 to 100 basis points. Urgent adjustments can bypass the regular weekly schedule through out-of-schedule executive votes.

Stability Fees and the Savings Rate

The stability fee and the DAI Savings Rate (DSR) form two sides of a monetary policy toolkit. Stability fees represent the protocol's revenue (collected from borrowers), while the DSR represents an expenditure (paid to DAI holders who deposit into the savings contract).

The spread between these two rates funds protocol operations. If the average stability fee across all vaults is 5%, the protocol might fund a DSR of 3.5%, with the remainder covering the surplus buffer, risk teams, and operational costs. This mirrors how traditional banks earn a net interest margin: the spread between their lending rates and deposit rates.

Following the Sky Protocol rebrand in September 2024, the system introduced the Sky Savings Rate (SSR) alongside the legacy DSR. The SSR applies to USDS holders (via the sUSDS yield-bearing token) and is intentionally set higher than the DSR to incentivize migration from DAI to USDS.

Peg Stability Mechanism

The stability fee's most critical function is maintaining the stablecoin's dollar peg. The mechanism works through supply and demand dynamics:

This operates alongside complementary mechanisms: the Peg Stability Module (PSM), which allows direct 1:1 swaps between DAI and approved stablecoins like USDC, and DSR adjustments that influence how much DAI is locked in savings versus circulating in the market.

Together, these tools function analogously to central bank policy instruments. The stability fee parallels a central bank lending rate, the DSR mirrors a deposit facility rate, and collateral ratios act like reserve requirements.

Comparison to Other Protocols

Not all DeFi borrowing costs work the same way. The stability fee model represents one of several approaches to pricing debt in decentralized protocols:

The key distinction: Maker's stability fee is a governance policy decision, while Aave and Compound rates adjust algorithmically based on supply and demand within lending pools. Liquity v1 eliminated ongoing interest entirely in favor of a one-time upfront fee. For a broader analysis of how these models generate sustainable revenue, see DeFi revenue models and sustainable tokenomics.

Comparison to Traditional Interest Rates

While stability fees serve a similar economic function to traditional lending rates, they differ in several important ways:

• Rate transmission is near-instant: once a governance vote passes and the GSM delay expires, new rates take effect on-chain within seconds, compared to weeks or months of pass-through lag in traditional banking
• Collateral is marked to market continuously via oracle price feeds, unlike traditional bank collateral that may be appraised periodically
• Operational costs are minimal since enforcement happens through smart contracts rather than legal processes, compliance staff, and physical infrastructure
• Correlation with central bank rates is weak: research from the Banque de France found that DeFi rates exhibit "unusually large and persistent spreads" compared to traditional short-term rates, and that policy rate transmission to DeFi lending is limited

Why It Matters

Stability fees are the primary mechanism that keeps overcollateralized stablecoins pegged to the dollar without relying on centralized issuers holding bank reserves. For the stablecoin ecosystem more broadly, the stability fee model proved that decentralized monetary policy is viable: DAI has maintained its peg through multiple market cycles since 2017, including the March 2020 crash and the UST collapse of 2022.

For builders and users in the Bitcoin ecosystem, understanding stability fees provides context for how stablecoin supply is managed. Protocols like Spark that facilitate stablecoin transfers on Bitcoin operate downstream of these issuance mechanics. When governance raises stability fees and DAI supply contracts, that can affect liquidity across every chain and layer where DAI circulates. For more on how stablecoins interact with Bitcoin infrastructure, see the analysis of stablecoins on Bitcoin.

Risks and Considerations

Governance Risk

Because rates are set by token holder votes, stability fee governance is subject to political dynamics. Large MKR/SKY holders (whales) can exert outsized influence on rate decisions. A poorly timed rate change could destabilize the peg or trigger a wave of liquidations if vault owners cannot afford the increased cost.

Rate Lag

While on-chain execution is fast, the governance process itself introduces delay. A stability fee change requires polling, voting, and the GSM security delay, a process that can take days. In fast-moving markets, the peg may drift significantly before governance can respond. The PSM helps bridge this gap for short-term deviations, but sustained depeg events require rate action that cannot happen instantly.

Cascade Effects

A sharp stability fee increase can force vault owners to repay debt rapidly to avoid mounting costs. If many vault owners close positions simultaneously, the resulting demand for DAI (to repay debts) can temporarily push DAI above its peg. In extreme cases, forced liquidations from undercollateralized vaults can cascade, amplifying market volatility.

Revenue Dependency

The protocol depends on stability fee revenue to fund the DSR, operational costs, and the surplus buffer. If borrowing demand drops (due to a bear market or competition from protocols with lower fees), revenue shrinks. This can force difficult choices: lower the DSR (making DAI less attractive to hold) or maintain it at a loss. The stablecoin yield landscape explores how these competitive dynamics play out across protocols.

This glossary entry is for informational purposes only and does not constitute financial or investment advice. Always do your own research before using any protocol or technology.