USDB Peg

USDB is a USD-pegged stablecoin issued by Bucket. The peg targets $1 and is supported on-chain by two components that work with open markets:

• Peg Stability Module (PSM) — a trustless 1:1 conversion rail between USDB and supported stablecoins, subject to a PSM fee.

• Market arbitrage — traders buy/sell across venues to close any price gap around $1.

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Peg Stability Module (PSM)

What it does

• Enables 1:1 conversions between USDB and supported stablecoins.

• A PSM fee applies.

Supported assets and fees

Direction	Asset	Fee
PSM IN (stablecoin -> USDB)	USDC	0%
PSM IN (stablecoin -> USDB)	suiUSDT	0.05%
PSM OUT (USDB -> stablecoin)	USDC, suiUSDT	0.30%

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Price Stability & Arbitrage

Let:

• price_usdb = USDB market price (USD) on DEX

• fee_in = PSM IN fee

• fee_out = PSM OUT fee

Scenario A — Upward depeg (USDB > $1)

1. Acquire USDB near $1 via PSM IN using a supported stablecoin.

2. Sell USDB on the market at price_usdb > 1.

3. Gross spread per USDB Spread_up ≈ price_usdb - (1 + fee_in)

4. Break-even check price_usdb > 1 + fee_in + (gas + slippage)

5. As selling pressure increases, price_usdb converges toward $1.

Scenario B — Downward depeg (USDB < $1)

1. Buy USDB on the market at price_usdb < 1.

2. Exit via PSM OUT to a supported stablecoin at ~$1 minus fee_out.

3. Gross spread per USDB Spread_down ≈ (1 - fee_out) - price_usdb

4. Break-even check price_usdb < 1 - fee_out - (gas + slippage)

5. As buying pressure increases, price_usdb converges toward $1.

Flash-mint assisted arbitrage

For capital efficiency, advanced users can use Flash Mint to source and retire USDB within one transaction, pairing the opposite leg through PSM or market liquidity to capture Spread_up or Spread_down as above.