About the Rotation Vault & stAMPL

Recall that timely rotations ensure the SPOT collateral set remains filled with fresh senior AMPL tranches so the system can be used to store stable value.

The Rotation Vault automates the process of rotations, so anyone can participate in rotations passively, through a staking mechanism. Stakers do not need to manage intermediate tranches or pay gas fees for each operation. With the current SPOT configuration, rotations happen weekly.

For an overview of how the rotation vault fits into the high level architecture of the SPOT protocol pelase see About Spot.

About stAMPL

stAMPL is a staked AMPL that represents a holders position in the rotation vault. The token is a freely redeemable claim on assets in the rotation vault. Additionally it pays or extracts an unsigned fee to those who stake. Like SPOT, stAMPL features free-floating price and proportional redemption.

Example 1: Imagine Alice has 1000 AMPL, the rotation vault also currently has 1000 AMPL in it, and there are 10K stAMPL in circulation. If Alice deposits all her holdings into the rotation vault she will own 50% of the assets in the vault. In return she will receive 10K stAMPL and total supply of stAMPL will increase to 20K stAMPL.

How the Rotation Vault Works

At present, rotations are configured to recur weekly. At the time of rotation, the vault automatically:

  • Tranches: Automatically separates AMPL into fixed-term seniors and juniors using SPOT's minting bond

  • Rotates: Automatically exchanges Maturing senior tranches for newly minted seniors into SPOT's collateral set.

The newly minted juniors created as a byproduct of tranching, remain in the rotation vault balance where they are held until they mature into raw AMPL, to be used for future rotations. The diagram below shows the flow of assets.

Referring to the diagram above, at the weekly time of rotation :

  1. The maturing Sr0 tranche rotates into the stAMPL vault and beomes raw AMPL. The maturing Jr0 tranche becomes raw AMPL.

  2. AMPL is tranched into fresh (Sr3, Jr3) pairs. The new Jr3 remains in the stAMPL rotation vault. The new Sr3 tranche rotates into the SPOT collateral set.

Note: In the case where the AMPL balance in the vault does not cover the entire rollover, it rotates as much as possible.

Rotation Vault

v2.0 — pending upgrade

The upcoming release of Rotation Vault v2 will include some important changes. These changes are relevant to all users currently participating in the stAMPL vault. Anybody currently staked in v1 will automatically transition into v2 through a contract upgrade in the near future. If you have questions about v1 or additional questions about v2, please feel free to contact us on the community discord channel.

Rotation Vault v2 introduces two key features. They serve to:

  • Facilitate SPOT <> AMPL arbitrage through Swapping

  • Balance demand for stability and leverage using a Dynamic Rotation Fee

We expect the effect of these two changes to impact market dynamics as follows:

  • Through Swapping — SPOT and AMPL prices will more closely resemble one another (though SPOT will not express supply volatility). SPOT supply will respond more elastically to demand through mint / redeem arbitrage. Increased demand for SPOT will result in SPOT minting and decreased demand for SPOT will result in SPOT redemption.

  • Through Dynamic Rotation Fees  The redeemable value of SPOT will enrich and debase based on the amount of the capital in the rotation vault.


v2.0 — pending upgrade

Today, we can see significant price deviation between SPOT and AMPL. This is largely due to the fact that when users mint or redeem SPOT, they receive tranched AMPL across four vintages. The Jr and Sr AMPL tranches held in the process of minting and redeeming, express amplified or insulated supply volatility until maturity, making it difficult for market makers to predictably execute mint and redeem arbitrage actions.

Rotation Vault v2 allows arbitrageurs to act simply on price deviations by swapping SPOT for AMPL directly and vice versa. For this reason we expect the price difference between SPOT and AMPL to decrease in the near term.

As a result, we expect increased SPOT supply elasticity. When the price of SPOT exceeds that of AMPL we expect minting to occur through arbitrage and when the price of SPOT is less than AMPL we expect redemptions to occur through arbitrage. Connecting demand for SPOT with the supply of SPOT prepares the system for scale.


v2.0 — pending upgrade

Vault v2 allows users to swap between AMPL and SPOT for a fixed percentage fee (5%), which goes to vault participants who provide liquidity for swapping. How Swaps Work Internally

When the vault has excess capital after rollovers, it allows users to swap AMPL for SPOT. Internally it:

  1. Tranches excess AMPL for Seniors and Juniors

  2. Uses seniors to mint SPOT

  3. Returns the minted spot back to the user

  4. Holds the Juniors until maturity

Alternatively, when users want to swap SPOT for AMPL the vault:

  1. Redeems the user’s SPOT tokens for senior tranches,

  2. Melds the senior tranches with the juniors it already holds (which are created during the normal course of rotation) to retrieve AMPL

  3. Returns AMPL to the user

Dynamic Rotation Fee

´v2.0 — pending upgrade

The rollover reward or fee is calculated based on the relative demand for stability and volatility (seniors and juniors) respectively.

Gauging Relative Demand

To gauge relative demand, the protocol looks at the balance of assets in the rotation vault relative to SPOT's total supply to determine a deviationRatio (dr):

dr=totalRolloverCapital/requiredRolloverCapitaldr = totalRolloverCapital / requiredRolloverCapital
  • totalRolloverCapital: is the total amount of AMPL in the rotation vault

  • requiredRolloverCapital: is the amount of AMPL required to sustain the SPOT supply.

At the time of rotation, a fee is applied by adjusting the exchange rate between tranches entering and exiting during the rotation operation.

  • When the dr = 1, the system is considered perfectly balanced. No rotation fee is applied.

  • When the dr < 1, the system is considered "under-subscribed", a positive rotation fee is applied which means spot holders are paying vault holders a percentage fee for rotation (for the privilege of stability). This results in spot debasement (or inflation)

  • When the dr > 1, the system is considered "over-subscribed", a negative rotation fee is applied which means vault holders are paying spot holders a percentage fee for rotation (for the privilege of leverage). This results in spot enrichment.

This fee percentage is applied based on a sigmoid function of the system’s deviation ratio. SPOT debasement is capped at 10% per annum and the enrichment is capped at 20% per annum.

Debasement & Enhancement

Debasement and enhancement is measured as the ratio between SPOT supply and senior AMPL tranches in SPOT's reserve.

When SPOT pays the Rotation Vault a reward on rotation, more senior tranches leave SPOT's reserve than enter it, debasing SPOT's value as measured in senior AMPL tranches.

Likewise, when SPOT extracts a reward from the Rotation Vault, more senior tranches enter SPOT's reserve than exit it, enhancing SPOT's value as measured in senior AMPL tranches.

Recall, parity changes between perp ratio and tranche ratio determine rollover rewards and fees, and thus have the effect of ultimately debasing and enhancing SPOT accordingly.

Steady State Vault Composition

At steady state, the rotation vault holds a combination of fixed-term junior AMPL tranches and raw AMPL (there are times when the vault will hold senior tranches as well, but this is rarely a significant portion of the vault, with most being paired with their junior tranche to combine back into AMPL). As a result, holding stAMPL is similar to holding a higher volatility AMPL. For more on this please see Volatility Amplification.

Additional Yield

Separately from the rollover reward and fee described above, stakers who deposit AMPL into the rotation vault automatically generate yield by:

  • Providing Tranche Liquidity: Users who want to redeem SPOT for AMPL before senior AMPL tranches reach maturity can take advantage of the junior AMPL tranches in rotation vault's collateral set to redeem for a fee. See Melding / Swapping.

  • Governance token (FORTH) Emissions: Users who hold stAMPL receive an emission of FORTH governance tokens based on the size of their position and time staked.

Volatility Multiple

The base rate volatility multiple of stAMPL can be calculated as a function of the quanitity of AMPL and junior tranches in the vault and the tranche ratio.

  • Lower (senior:junior) tranche ratios correspond with higher volatility stAMPL.

  • Higher (senior:junior) tranche ratios correspond with lower volatility stAMPL.

n=juniors+amplr=f(tranche_ratio)vault_multiple=(ampl+rjuniors)/nn = juniors + ampl\\ r = f(tranche\_ratio)\\ vault\_multiple = (ampl + r * juniors)/n

Rollovers Halting

Recall that in the SPOT collateral set if rotations halt the senior AMPL tranches mature progressively into raw AMPL which makes the SPOT token more volatile (bending rather than breaking). Similarly, in the rotation vault if rotation halt, the junior AMPL tranches mature progressively into raw AMPL. However, in this case the net effect is the collateral in the rotation vault becomes less volatile, because raw AMPL is less volatile than juniors.

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