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Overview

USDY is Ondo’s yield-bearing token that provides investors a steady return over time. The token price started at $1.00 in July 2023 and has increased over time at a variable monthly rate. For a product-level introduction, see USDY Basics. The USDY_InstantManager contract is the on-chain entry point used by the Ondo web app to instantly mint and redeem USDY. You can call it directly from your own contracts or EOA to:
  • Convert USDC into USDY via subscribe (selector 0x22d4a175)
  • Convert USDY back into USDC via redeem (selector 0xd8780161)
Addresses for USDY, USDY_InstantManager, and the USDY redemption price oracle are listed in Smart Contracts → Addresses.
The Ethereum USDC address used in the examples below is 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48.

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Prerequisites

Before calling subscribe or redeem, the address that interacts with the contract must be registered in the OndoIDRegistry. You can whitelist your address at app.ondo.finance/account/wallets. If you run into issues, reach out to support@ondo.finance.
Transactions from an address that is not registered in the OndoIDRegistry will revert with UserNotRegistered. Contract wallets and smart-contract integrations must whitelist the exact calling address.

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ERC20 approvals

The USDY_InstantManager pulls tokens from your wallet via transferFrom, so you must approve it to spend the token you are sending before calling subscribe or redeem:
  • Before subscribe: approve the manager to spend your deposit token (e.g. USDC) for at least depositAmount.
  • Before redeem: approve the manager to spend your USDY for at least rwaAmount.
Each approval is a separate transaction — typically IERC20(token).approve(usdyInstantManager, amount). If you skip this step, the subscribe/redeem call will revert with an ERC20 allowance error such as ERC20: insufficient allowance.

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Subscribing: USDC to USDY

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Function signature

function subscribe(
    address depositToken,
    uint256 depositAmount,
    uint256 minimumRwaReceived
) external returns (uint256 rwaAmountOut);

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Parameters

  • depositToken: the token being deposited (typically USDC)
  • depositAmount: the amount of depositToken to deposit, in the token’s native decimals (e.g. 1000000 for 1 USDC)
  • minimumRwaReceived: slippage protection, denominated in USDY’s 18 decimals. Because you are minting directly with Ondo, there is no front-running or order-size slippage, so 0 is safe.

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Example

// Swap 100 USDC for USDY
IERC20(USDC).approve(usdyInstantManager, 100e6);
uint256 usdyReceived = usdyInstantManager.subscribe(
    USDC,
    100e6, // 100 USDC (6 decimals)
    0      // no slippage expected when minting directly
);

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Redeeming: USDY to USDC

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Function signature

function redeem(
    uint256 rwaAmount,
    address receivingToken,
    uint256 minimumTokenReceived
) external returns (uint256 receiveTokenAmount);

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Parameters

  • rwaAmount: the amount of USDY to redeem, in USDY’s 18 decimals (e.g. 1000000000000000000 for 1 USDY)
  • receivingToken: the token to receive (typically USDC)
  • minimumTokenReceived: slippage protection, denominated in the receiving token’s native decimals. 0 is safe when redeeming directly with Ondo.

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Example

// Redeem 100 USDY for USDC
IERC20(USDY).approve(usdyInstantManager, 100e18);
uint256 usdcReceived = usdyInstantManager.redeem(
    100e18, // 100 USDY (18 decimals)
    USDC,
    0       // no slippage expected when redeeming directly
);

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USDY price oracle

The USDY price is published on-chain by the RWADynamicOracle contract (see the “Redemption Price Oracle” row in /addresses). Rather than storing a single current price, the oracle is configured with a series of ranges — each range has a start time, end time, and a daily interest rate that compounds across the range. The USDY_InstantManager consults this oracle on every subscription and redemption to convert between USD value and USDY amounts. All prices are denominated in USD with 18 decimals and rounded to 8 decimal places.

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Get the current price

function getPrice() external view returns (uint256 price);
function getPriceData() external view returns (uint256 price, uint256 timestamp);
  • getPrice(): returns the current USDY price, in USD with 18 decimals.
  • getPriceData(): convenience wrapper that also returns the current block timestamp.
Both revert if the oracle is paused. 
uint256 price = usdyOracle.getPrice();
// e.g. 1.087543210000000000 → 1087543210000000000

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Get a historical price

function getPriceHistorical(uint256 timestamp) external view returns (uint256 price);
Returns the USDY price at the given Unix timestamp, in USD with 18 decimals.
If timestamp precedes the oracle’s first configured range (i.e. before USDY existed on-chain), getPriceHistorical returns 0. Callers should check for a non-zero return value before using the result.
Unlike getPrice(), this function does not revert when the oracle is paused. 
uint256 oneYearAgo = block.timestamp - 365 days;
uint256 pastPrice = usdyOracle.getPriceHistorical(oneYearAgo);
require(pastPrice > 0, "Timestamp precedes oracle start");

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Converting between USD and USDY

The oracle price represents how many USD one USDY is worth. 
// USDY amount (18 decimals) → USD value (18 decimals)
uint256 usdValue = (usdyAmount * oracle.getPrice()) / 1e18;

// USD value (18 decimals) → USDY amount (18 decimals)
uint256 usdyAmount = (usdValue * 1e18) / oracle.getPrice();

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Reference

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Decimal handling

  • USDC: 6 decimals (1 USDC = 1,000,000 units)
  • USDY: 18 decimals (1 USDY = 1018 units)
  • Oracle prices: 18 decimals, rounded to 8 decimal places

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Rate limits and minimums

The manager contract enforces per-user and global rate limits, as well as a configured minimum USD value per subscription and redemption. Very small or unusually large transactions may revert.

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Common errors

ErrorMeaning
SubscriptionsPaused / RedemptionsPausedOperations are temporarily paused on the manager
TokenNotAcceptedThe specified deposit or receiving token is not supported
UserNotRegisteredThe caller is not registered in the OndoIDRegistry
DepositAmountTooSmall / RedemptionAmountTooSmallTransaction is below the configured USD minimum
RwaReceiveAmountTooSmall / ReceiveAmountTooSmallOutput is less than the specified minimum
Compliance revertThe caller failed the OndoCompliance check (e.g. sanctions, jurisdiction)
Rate-limit revertThe transaction exceeds per-user or global rate limits

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Best practices

  1. Ensure the calling address is whitelisted in the OndoIDRegistry before attempting any transaction.
  2. Check the contract’s pause status (subscribePaused / redeemPaused) before attempting transactions.
  3. Approve the USDY_InstantManager for the exact amount being deposited or redeemed.
  4. Implement proper error handling for all possible revert conditions.

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Resources