Emerald Documentation
Emerald is a fixed-yield vault for stablecoins. You deposit USDC, our optimizer locks in the best risk-adjusted rate it can find on Pendle Finance, and you earn a predictable return. No active management, no annual fees, withdraw anytime.
25+
Markets evaluated
Arbitrum
Live network
0.5%
One-time fee
$100
Suggested minimum
Why Emerald
Most ways to earn on stablecoins involve a tradeoff. Variable-rate lending (Aave, Compound) means your APY can drop overnight. Yield aggregators (Yearn) take 2% management plus 20% of profits. Earn programs at centralized exchanges custody your tokens and lock them up. Manual Pendle requires picking markets, watching maturities, and paying gas per trade. Emerald is built around a different tradeoff: you give up theoretical maximum APY in exchange for a predictable, professionally allocated return with no recurring fees.
The yield you see is the yield you get
Emerald buys Principal Tokens (PTs) that lock in a fixed payout at maturity. When the dashboard shows 6.5% net APY, that is what your shares earn — not an estimate that adjusts when borrow demand changes.
Risk-adjusted, not yield-chased
Other vaults rank markets by APY. Emerald applies a 0–20% haircut to underlying stablecoins based on depeg risk, then ranks. The number you see is already pessimistic — it accounts for tail risk in the collateral, not just the rate on the screen.
Every cost is shown upfront
Net APY = Gross APY – entry costs – exit costs. We decompose bridge fees, gas, swap slippage, and AMM spread on every market. If your $200 deposit costs more in fees than it earns in the next 6 months, the dashboard will tell you so. No buried fees.
Multi-chain routing handled for you
The vault deploys into the best risk-adjusted Pendle markets on Arbitrum after all costs. The keeper handles swapping and execution; you only sign one transaction on Arbitrum. No second wallet, no juggling networks.
No annual fees, no performance fees
A typical aggregator charges ~2% per year plus 20% of yield. At 6.5% net APY over 5 years on $100K, that is roughly $2,400 in fees you do not pay with Emerald. We charge 0.5% once on entry. After that, you keep 100% of net APY.
Withdraw anytime
The vault keeps 10% as idle USDC for instant withdrawals. Larger amounts liquidate PTs on Pendle's AMM in 15–30 seconds. No multi-day exit windows, no bonding periods, no waiting queues. If rates change and you want out, you are out.
The keeper shows its work
Every rebalance decision is logged with full reasoning: "Held position X because rotating to Y would have cost 1.4% in entry/exit fees and only saved 0.6% in APY." If something looks off, you can audit why. Most vaults do not expose this.
You own the shares — non-custodial
Your USDC sits in an ERC-4626 vault contract that you can verify on Arbiscan, not in our wallet. The keeper signs transactions on the vault's behalf but cannot withdraw your funds. If the keeper goes offline tomorrow, your USDC and any PT positions are still yours to redeem.
Numbers are sacred
The dashboard, the API, and the landing show the same numbers. Estimates are labeled. Unknowns show as "—", not as zero. We treat data integrity the way a Bloomberg terminal does — if a number lies, we fix the bug, we don't paper over it.
How It Works
You deposit USDC
Connect your wallet on Arbitrum and deposit USDC. Suggested minimum is $100 with a one-time 0.5%entry fee. After that, you keep 100% of your yield — no annual or performance fees.
Markets are scored
The optimizer continuously scans Pendle markets and deploys on Arbitrum. Each market is ranked by net APY after gas, bridge cost, swap slippage, AMM spread, and underlying-asset risk haircut.
Capital is deployed to Pendle
An automated keeper buys Principal Tokens (PTs) on the highest-ranked markets. The keeper consolidates duplicate positions and respects per-market caps so the vault does not move prices.
Yield accrues until maturity
As PTs approach maturity, their value converges toward the guaranteed payout. When a position matures, the keeper redeems it and rolls into the next-best opportunity automatically — no action needed from you.
Withdraw anytime
No lockup. The vault keeps 10% idle for immediate withdrawals; larger amounts liquidate PTs on Pendle's AMM in 15–30 seconds. Slippage is shown before you confirm.
Pendle Integration
What is a Principal Token?
A Principal Token (PT) represents the principal portion of a yield-bearing asset on Pendle. When you buy a PT at a discount, you lock in a fixed yield that you receive at maturity.
Example: if PT-sUSDe with 6 months to maturity trades at $0.96, holding it until maturity guarantees roughly 8.3% annualized return. This is the "Yield to Maturity" (YTM) shown in the app.
PTs are fully on-chain, backed by underlying collateral in Pendle's contracts. At maturity they redeem 1:1 for the underlying asset.
Why Pendle
Emerald routes 100% of deployed capital through Pendle Finance. This is a deliberate choice:
- 1.Mature primitive. Pendle has been operating since 2021 and is currently the largest fixed-yield protocol in DeFi by TVL.
- 2.Multiple audits. Audited by ChainSecurity, Dedaub, and Spearbit. Reports are public.
- 3.Liquid fixed income. Principal Tokens are the only mature, liquid implementation of on-chain fixed yield. PTs trade actively — you can exit before maturity.
- 4.Reduced surface area. Routing through one well-audited protocol means fewer external dependencies and failure points than a multi-protocol aggregator.
Risk Model
Not all stablecoins carry the same risk. Emerald applies a haircut to each underlying asset based on its depeg history, mechanism complexity, and protocol maturity. The APY you see on the dashboard is already net of these haircuts — you compare realistic yields, not theoretical maximums.
| Asset Type | Haircut | Examples |
|---|---|---|
| Established | 0% | sDAI, aUSDC |
| Moderate | 10% | sUSDe, USDe |
| Higher risk | 20% | Newer synthetics |
A 10% haircut means a market offering 12% raw APY shows as 10.8% net APY. The keeper uses the haircut-adjusted number when ranking — so it does not pile capital into a high-rate market simply because the rate looks attractive on paper.
Operations
The vault is run by an automated keeper that handles deployment, rebalancing, position consolidation, and maturity rollovers. Every cycle is logged on-chain and visible in the dashboard.
- ●10% idle reserve. Always kept in USDC for immediate withdrawals.
- ●Continuous evaluation. The keeper runs every 5 minutes; route caches refresh every 10 minutes; NAV reports every hour.
- ●Switching cost gate. Rotations only happen if net benefit (APY gain – entry/exit costs, annualized) is positive over the position's remaining duration.
- ●Decision log. Every keeper cycle records its reasoning. The dashboard shows the latest decision and why.
- ●On-chain transparency. All vault operations execute on Arbitrum and are visible on Arbiscan.
Risks
Honest disclosure. Each of these risks exists, but Emerald is structured to keep them as low as the product allows: we route through the most-audited fixed-yield protocol in DeFi, we use a standard ERC-4626 vault (no novel primitives), and the optimizer only allocates where the risk-adjusted return clears the bar. Read this section before depositing.
Specific to Emerald
1. Smart contract audit pending
A formal third-party audit of the Emerald Vault is in our short-term roadmap. Until then we rely on extensive test coverage, open-source code, and the use of a standard ERC-4626 implementation — not novel primitives. The risk exists; it's a known gap we are actively closing.
2. 100% Pendle concentration
Emerald routes all deployed capital through Pendle Finance. This is a deliberate choice — Pendle has been operating since 2021 and is audited by ChainSecurity, Dedaub, and Spearbit, making it the most de-risked fixed-yield protocol available.
3. Multi-layer access control with one residual single-key surface
The vault separates three authorities, each with a strictly limited scope:
- Owner — a TimelockController on Arbitrum with a 24-hour delay. Any admin change (rotating the keeper, adjusting fees, changing deposit caps, unpausing) is publicly visible 24 hours before it can take effect.
- Guardian — a 2-of-2 Gnosis Safe on Arbitrum that can only pause the vault in an emergency. It cannot unpause or move funds.
- Keeper — a single hot key, restricted to allocation and redemption only. Single-key by design: the keeper signs every 5 minutes, which a multisig cannot match. It cannot withdraw user funds or change parameters.
The residual single-key surface is the keeper. A compromised keeper key could route capital into suboptimal PT positions (losing some value to slippage), but cannot drain user funds — the contract limits its scope. The Guardian Safe can pause within seconds to stop further damage.
4. AMM-based exits for large withdrawals
The vault keeps 10% as idle USDC for instant withdrawals. Larger amounts liquidate PTs on Pendle's AMM. Slippage is typically under 0.5% in normal conditions but can be higher or take longer in market stress.
General to DeFi and crypto (and how we manage them)
These are not Emerald-specific — they apply to any similar product:
Stablecoin depeg and underlying-protocol risk
Stablecoins can lose their peg; smart contracts can have bugs. We don't pretend these are zero. We apply a haircut (0%, 10%, or 20%) to each underlying based on depeg history and mechanism complexity, and we only allocate when the risk-adjusted net APY — after haircut and after entry/exit costs — is positive. A market with a flashy headline rate that doesn't survive the haircut + cost subtraction simply does not get capital, no matter how attractive it looks.
Wallet and key security
Your private key, hardware wallet, and seed phrase are your responsibility. Lost keys cannot be recovered.
Regulatory environment
DeFi is in a changing regulatory landscape; access may be restricted in some jurisdictions. You are responsible for compliance with applicable laws.
Emerald is open and verifiable. View vault contract on Arbiscan