Synthetic and Delta-Neutral Stablecoin Risks Explained

Video transcript

A synthetic stablecoin holds its peg with crypto hedged by short derivatives, not bank reserves. That design breaks in its own ways.

Take Ethena's USDe. Hold ETH, short the same amount in perpetual futures, and the short gains what the collateral loses. The trade also earns funding and staking yield.

When funding turns negative, the hedge pays. Ethena's docs show ETH perp funding was negative on 17.5 percent of days over three years, so check the reserve fund against supply.

The peg also depends on custodians, venues and who can redeem. USDe briefly fell below 66 cents on Binance in October 2025, and Stream's xUSD traded at 26 cents by November 4 after a fund manager's loss.

The hedge can hold and the token still fail at the mint. An attacker minted 80 million unbacked Resolv USR through a privileged offchain key with no onchain cap. Within 17 minutes, it traded at 2.5 cents.

Score each risk on dated evidence, from funding to mint keys. Rescore when funding turns negative, a venue or custodian changes, or the mint contract upgrades.

Guardian underwrites onchain positions by reviewing code, control, dependencies and economic failure paths, then scoring each from 0 to 100. The article itself gives no verdict on USDe.

Read the full article for the scoring table, or talk to Guardian about underwriting a synthetic dollar.

A fiat-backed stablecoin holds cash-like reserves and redeems through its issuer. A synthetic dollar holds crypto plus a short hedge, and earns from the trade.

That design fails in its own ways. Three events since October 2025 show them: one exchange pricing USDe below $0.66, a fund manager loss behind Stream's xUSD, and an unbacked mint of Resolv's USR.

This post gives no verdict on USDe or any other stablecoin.

How Synthetic Dollars Hold Their Peg

Ethena describes USDe as "a synthetic dollar, backed with crypto assets and corresponding short futures positions."

The idea is a delta-neutral position. Hold ETH, and short the same amount of ETH perpetual futures.

If ETH falls, the short gains what the collateral loses. The dollar value of the pair stays roughly flat.

The position also earns. Ethena's docs name four revenue sources:

• Staking yield on liquid staking tokens (LSTs).
• Funding paid to short perpetual positions.
• The basis on short-dated futures.
• Rewards on liquid stablecoins held as backing.

Each of those depends on a market, a venue or a custodian. That is where the risks sit.

Funding Rate and Basis Risk

Perpetual futures use a funding rate to stay near spot. When it is positive, longs pay shorts and the hedge earns.

When it turns negative, the hedge pays. Ethena defines funding risk as "the potential of persistently negative funding rates."

Its docs cite three years of funding history, as of December 31, 2024:

• Funding was negative on 17.5% of days for ETH perps and 15.9% for BTC.
• With staked ETH income added, combined revenue was negative on 8.84% of days.
• The longest negative funding streak was 13 days.

Ethena cautions that this history may not reflect its own market impact.

Its buffer is a reserve fund, which covers negative revenue and backing shortfalls. In low-funding periods, more backing moves into liquid stablecoins.

Ethena's docs say 0% of revenue currently flows into the reserve fund.

Basis risk

Basis risk is the gap between what you hold and what you hedged. Ethena calls it backing assets risk: a backing asset that "differs from the underlying asset" of the hedge.

Staked ETH against an ETH short is the standard case. Ethena says staked ETH was about 6% of backing in January 2025.

Exchange and Custodian Risk

The hedge lives on exchanges. In Ethena's design, the collateral does not.

Ethena holds backing with off-exchange settlement (OES) providers, in segregated accounts using bankruptcy-remote trusts or MPC wallets. It says no backing assets are ever deposited with an exchange.

Its exposure to a failed exchange is the profit and loss not yet settled. Copper's Clearloop, its docs say, settles daily.

If an exchange failed, Ethena would move the collateral to another exchange and re-hedge.

That moves the risk to the custodian. Ethena lists three custodial risks:

• Access to deposits, withdrawals and delegation.
• The custodian's duties if an exchange fails.
• Operational failure of the custodian itself.

Venue pricing

On October 10, 2025, during a market-wide crash, USDe briefly fell below $0.66 on Binance. Other venues did not show as large a move, The Block reported.

Ethena Labs CEO Guy Young said Binance priced USDe from its own thinner order book.

He said minting and redemption worked "perfectly," with about $2 billion of USDe redeemed in 24 hours.

Binance said it paid about $283 million in compensation across USDe, BNSOL and WBETH.

A lending or margin market that values a synthetic dollar from one venue inherits that venue's liquidity.

Offchain managers

Not every yield-bearing dollar publishes its positions. On November 3, 2025, Stream Finance said an external fund manager had lost about $93 million of its funds.

Stream suspended withdrawals and deposits. Its xUSD traded at $0.26 by November 4, Decrypt reported, citing CoinGecko.

Elixir had lent about $68 million to Stream, roughly 65% of the backing of its deUSD. By November 18, Protos described Elixir's sdeUSD as 99.8% depegged.

Our vault curator risk guide traces how those losses reached lending vaults.

Redemption and Liquidity Risk

Most holders cannot redeem directly. Ethena's direct mint and redeem are "exclusively for approved market making counterparties" that clear KYC/KYB checks.

Everyone else buys and sells on AMM pools, so most holders exit at the pool price.

Staking adds a queue. Ethena's admin role can set the sUSDe cooldown up to a maximum of 90 days.

Ask three questions:

• Who can redeem, at what size, and how fast?
• What is the cooldown today, and who can change it?
• How deep are the pools you would exit through?

Smart Contract and Mint Risk

The hedge can hold and the token can still fail at the mint.

Resolv's USR used a delta-neutral hedging strategy, The Block reported. On March 22, 2026, an attacker minted 80 million unbacked USR.

The collateral pool was never touched, per Rekt. Minting relied on a privileged offchain key with no onchain cap on what it could authorize.

Within 17 minutes of the first mint, USR traded at $0.025 on Curve. About $25 million was extracted, The Block and Rekt reported.

Gathering the multisig signatures to pause took about three hours, Rekt said.

Our infinite mint guide covers the pattern.

So check the limits written into the contract. Ethena, for example, sets global mint and redeem limits per Ethereum block, adjustable by its Dev multisig.

• Is there an onchain cap per transaction, block or period?
• Who holds the mint signer, and how is it stored?
• Can a pause execute in minutes, not hours?
• Is supply monitored against backing in real time?

How to Score a Synthetic Dollar

Score each risk on dated evidence. Our stablecoin risk assessment template gives the weights; these are the synthetic-specific checks.

Rescore when funding turns negative, a venue or custodian changes, or the mint contract upgrades.

Our stablecoin depeg history shows how fast a peg can go.

How Guardian Helps

Guardian underwrites onchain positions for capital allocators. It reviews the deployed code, who controls it, its dependencies and its economic failure paths.

Each position gets a score from 0 to 100, and the score moves when the protocol changes.

Since May 2025, Guardian has reviewed Ethena's timelock, onchain minting contracts, Safe execution guard, peg-stability module and EthenaPay wallet.

Read the onchain minter report or the Ethena case study.

Frequently Asked Questions

What is a synthetic stablecoin?

A token that tracks the dollar using crypto collateral hedged with short derivatives, rather than cash reserves. Ethena describes USDe as a synthetic dollar backed by crypto assets and corresponding short futures positions.

What happens when funding rates turn negative?

The short hedge pays funding instead of earning it. Ethena covers negative revenue from a reserve fund and shifts backing into liquid stablecoins. Long negative periods drain the buffer, so check its size against supply.

Did USDe depeg in October 2025?

On October 10, 2025, USDe briefly traded below $0.66 on Binance, The Block reported. Ethena's CEO said Curve, Fluid and Uniswap moved 30 basis points or less, and redemptions kept working. Binance compensated affected users.

How is a synthetic dollar different from a fiat-backed stablecoin?

Both target $1. A fiat-backed stablecoin holds cash-like reserves redeemable from its issuer. A synthetic dollar holds crypto and short hedges, so its peg also depends on venues, custodians and the firms allowed to redeem.

Sources

• Ethena docs: Ethena Overview
• Ethena docs: Funding Risk
• Ethena docs: Backing Assets Risk
• Ethena docs: Custodial Risk
• Ethena docs: Exchange Failure Risk
• Ethena docs: Reserve Fund
• Ethena docs: Mint and Redeem Contract V2
• Ethena docs: Staking Key Functions
• The Block: Binance pays $283 million in compensation following Friday's depegs (October 12, 2025)
• Cointelegraph: Explanations of USDe 'depeg' on Binance focus on coordinated attack, oracles (October 12, 2025)
• Decrypt: Stream Finance stablecoin plunges 77% after fund manager loses $93 million (November 4, 2025)
• Protos: High yields to haircuts: has DeFi learned anything from yield vault collapse? (November 18, 2025)
• The Block: Resolv's USR stablecoin depegs after attacker mints 80 million unbacked tokens (March 22, 2026)
• Rekt: Resolv Labs, Rekt (April 7, 2026)
• Guardian: Securing Ethena's ecosystem
• Guardian: Ethena Onchain Minter report