sUSDB and Yield

This page covers two layers of yield for USDB stablecoin holders:

• sUSDB and BSR: stake USDB to get sUSDB; value appreciates via an increasing exchange rate driven by the Base Savings Rate (BSR).

• sUSDB Savings Pool: deposit sUSDB to sUSDB Savings Pool to earn additional Sui rewards on top of BSR.

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sUSDB and BSR

What is BSR

The Base Savings Rate (BSR) is Bucket’s fixed savings rate for USDB. It does not apply to idle USDB by default. When activated, BSR accrues in real time by increasing the exchange rate between sUSDB and USDB. The app shows your fixed APR for BSR and the current exchange rate.

What is sUSDB

sUSDB is the yield-bearing stablecoin you receive when you stake USDB into the staking pool to activate BSR. Yield does not change your sUSDB balance; instead, each unit of sUSDB represents more USDB over time as the exchange rate rises.

Mechanics

• Stake USDB -> mint sUSDB at the current exchange rate.

• Unstake sUSDB -> receive USDB at the live exchange rate.

• Balances and the exchange rate update in real time.

• No stake or unstake fee. No lockup.

Formulas

minted_sUSDB = staked_USDB / exchange_rate

unstaked_USDB = sUSDB_balance * exchange_rate

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sUSDB Savings Pool

What it is

• A savings pool for sUSDB that pays additional Sui rewards (Savings Yield) on top of BSR.

What you earn

• Savings rewards accrue continuously and are claimable at any time.

• Your app-level Estimated APR shows the combined rate: BSR + SUI rewards APR.

Deposit and withdraw

• Deposit sUSDB into the sUSDB Savings Pool to start earning Sui rewards.

• Withdraw whenever you want with no fees.