Ondo Finance

USDY vs rUSDY: accrual mechanics

USDY ships in two interchangeable forms so integrators choose the right unit of account. The economics are identical — both earn the yield on short-term Treasuries and bank deposits — but the balance/price behavior differs.

• USDY (accruing): fixed balance, rising price. The token's reference price updates each business day and drifts above $1.00 as interest compounds — like a money-market NAV.
• rUSDY (rebasing): fixed ~$1.00 price, growing balance. Yield arrives as additional rUSDY tokens, so it behaves like a normal stablecoin in UIs and DeFi accounting.
• Convertible 1:1 in value between the two via the rUSDY wrapper.
• rUSDY is the friendlier primitive for payments/DeFi where a clean $1 unit matters; USDY suits treasuries that want a single non-rebasing holding.

OUSG instant mint/redeem & BlackRock backing

OUSG is the institutional product and the liquidity engine behind Ondo Nexus. Unlike wire-based fund subscriptions, OUSG can be minted and redeemed on-chain in USDC around the clock through InstantManager contracts.

• Backing is dominated by BlackRock's BUIDL tokenized money-market fund plus short-term Treasury ETFs.
• Instant subscribe converts USDC → OUSG; instant redeem converts OUSG → USDC, both gated to OndoIDRegistry-registered qualified investors.
• Guardrails: $50M global / $25M per-investor instant-mint caps per 24h; $5K instant / $50K non-instant redemption minimums.
• Nexus reuses this engine to offer instant redemption across third-party tokenized Treasuries (Franklin Templeton, Wellington, WisdomTree).

Ondo Chain & Global Markets strategy

Ondo is moving up the stack from issuing RWA tokens to owning the rails. The thesis: institutions won't run core markets on fully permissionless chains, but want public-chain composability — so Ondo is building an L1 that bridges both, plus a securities platform to bring stocks on-chain.

• Ondo Chain: permissioned validators (regulated institutions) for trust + open access for developers; RWA-backed staking and enshrined oracles reduce reliance on third-party price feeds.
• Global Markets: tokenized US equities/ETFs via API, extending Ondo's Treasury playbook to the broader securities market ($6.8B+ volume since Sep 2025).
• Ondo Catalyst: a $250M fund with Pantera (Jul 2025) seeding RWA protocols/infrastructure — building an ecosystem around Ondo's rails.
• Vertical stack — products + Nexus liquidity + Global Markets + L1 — is the real moat vs. single-product T-bill issuers like Mountain.

Regulatory & risk posture

• USDY and OUSG are explicitly restricted from US persons and gated by KYC/registry (OndoIDRegistry) — a compliance-first, non-US framing.
• Yield is the risk-free rate minus fee, so Fed rate cuts directly compress returns.
• Off-chain dependencies: Treasury custodians, BlackRock's BUIDL fund, and USDC liquidity for instant redemption.
• Issuance via offshore entities (e.g. Ondo Global Markets BVI / Ondo USDY LLC) carries legal-structure and bankruptcy-remoteness considerations. [verify entity details]

Architecture

Ondo exposes its products as standard tokens (USDY/rUSDY 18-decimal ERC-20s; OUSG) plus on-chain 'InstantManager' contracts that handle subscribe (USDC → RWA) and redeem (RWA → USDC). Access is permissioned: a caller must be registered in the OndoIDRegistry (KYC for non-US qualified investors) and must approve the manager contract to spend its tokens before any mint/redeem. There is no separate REST API for mint/redeem — integration is direct smart-contract calls; ONDO governance and reference-price updates happen on-chain.

Integration shape

To embed USDY/OUSG: (1) get the integrating wallet KYC'd into the OndoIDRegistry, (2) approve the USDY_InstantManager / OUSG_InstantManager for USDC and the RWA token, (3) call subscribe()/redeem() with slippage bounds. USDC is 6 decimals; USDY/OUSG are 18 decimals, so amounts must be scaled accordingly (e.g. 100e6 USDC, 100e18 USDY).

API surface

subscribe(depositToken, depositAmount, minimumRwaReceived)

InstantManager: convert USDC → USDY/OUSG. minimumRwaReceived is slippage protection in the RWA's 18 decimals (0 is safe for direct minting).

redeem(rwaAmount, receivingToken, minimumTokenReceived)

InstantManager: convert USDY/OUSG → USDC. minimumTokenReceived is in the receiving token's decimals.

OndoIDRegistry (KYC gate)

Caller address must be registered/whitelisted before subscribe/redeem succeed.

ERC-20 approve()

Approve the InstantManager to spend USDC (mint) or the RWA token (redeem) first.

rUSDY wrap/unwrap

Wrap accruing USDY into rebasing rUSDY (or back) for a clean $1.00 unit in DeFi. [verify exact wrapper method names]

Minimal integration

Instant-mint USDY with 100 USDC via the USDY_InstantManager (ethers v6).

import { Contract, parseUnits } from 'ethers';

const USDC  = '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48'; // 6 decimals
const USDY_INSTANT_MANAGER = '0xa42613C243b67BF6194Ac327795b926B4b491f15';

// caller wallet must already be registered in the OndoIDRegistry (KYC)
const usdc = new Contract(USDC, ['function approve(address,uint256) returns (bool)'], signer);
await usdc.approve(USDY_INSTANT_MANAGER, parseUnits('100', 6));

const manager = new Contract(
  USDY_INSTANT_MANAGER,
  ['function subscribe(address depositToken, uint256 depositAmount, uint256 minimumRwaReceived)'],
  signer,
);
// 100 USDC -> USDY; 0 minOut is safe for direct minting (no AMM)
await manager.subscribe(USDC, parseUnits('100', 6), 0n);

Build notes

• Decimals mismatch is the classic bug: USDC is 6 decimals, USDY/OUSG are 18 — scale amounts per token, not a shared constant.
• Mint/redeem are gated: an un-registered address will revert. Onboard the wallet to the OndoIDRegistry first (non-US qualified investors only).
• OUSG instant flows have caps ($50M global / $25M per investor per 24h) and minimums ($5K instant / $50K non-instant redeem) — handle revert/queue cases.
• [verify current addresses against docs.ondo.finance/addresses before mainnet use — proxies and per-chain addresses change]