Oracle Extractable Value (OEV)

Oracle extractable value (OEV) is the profit that can be captured by the first party to act on a fresh price update from a blockchain oracle. When an oracle publishes a new price, some positions in DeFi protocols may suddenly become eligible for liquidation, or a price gap may open between a protocol and the wider market. Whoever gets their transaction in immediately after the update can claim liquidation bonuses or arbitrage profits.

OEV is a specific category within maximal extractable value (MEV), the broader term for profit available from ordering transactions in a block. The term became common from around 2023, as oracle providers and lending protocols began to argue that this value, which normally flows to specialised traders and block builders, should be partly returned to the protocols and users whose activity creates it.

Imagine a pawnshop that checks the official price of gold only once an hour. When the new price is posted and it is lower, some loans backed by gold are suddenly under-secured, and the shop pays a finder's fee to whoever closes those loans first. A crowd of fast runners waits by the noticeboard, ready to sprint the moment a new price goes up.

The finder's fee is the oracle extractable value. The shop and its customers do not benefit from the race; the runners and whoever controls the queue at the counter do. OEV designs try to auction the right to be first and give part of the proceeds back to the shop.

Lending protocols such as Aave and Compound let users borrow against collateral, and they rely on oracle prices to decide when a loan is unsafe. When a price update pushes a borrower below the required collateral level, the position becomes open to liquidation: a third party repays part of the debt and receives collateral at a discount, the liquidation bonus. The steps are:

1. The oracle submits a price-update transaction.
2. Searchers, automated bots that hunt for profit, detect that the update will make certain positions liquidatable.
3. They compete to place a liquidation transaction directly after the update, often by paying large fees or bribes to block builders.
4. The winner collects the bonus; most of the competition's value tends to flow to block producers through those fees.

Because the bonus is paid out of the borrower's collateral, the value leaves the protocol's users and ends up with outside parties.

Several designs aim to redirect OEV:

• Auctioned updates. The right to submit, or to act right after, a particular price update is sold in an auction, and the proceeds go to the protocol that uses the oracle. API3 developed an "OEV Network" around this idea.
• Delayed public updates. Some systems delay releasing an update to the public mempool for a short time while a private auction runs, then fall back to normal publication if no bid arrives. UMA's Oval, built with Flashbots, followed this pattern.
• Oracle-integrated recapture. Large oracle networks, including Chainlink, have introduced services that return part of liquidation-related MEV to integrated lending markets.

These approaches share a goal: protocols can use recaptured value to lower borrowing costs, fund reserves or reward users. They draw on wider work on MEV protection and auction design.

For a decentralised lending protocol, OEV is a hidden cost. Liquidation bonuses must be large enough to attract liquidators in stressed markets, but when competition is intense, most of the bonus is not needed to motivate liquidators and simply leaks to block builders. Recapturing it can make protocols more efficient. OEV also affects oracle design choices: frequent updates reduce the gap between market and oracle prices, shrinking OEV, but cost more in network fees. Protocols on chains with centralised sequencers, such as many layer 2 networks, face different dynamics, since the sequencer controls ordering.

OEV auctions add moving parts and new trust assumptions. If an auction or relay fails, a price update could be delayed, leaving a protocol temporarily using stale prices during a market crash. Critics also note that concentrating the right to liquidate in a few auction winners could reduce competition over time. OEV is distinct from oracle manipulation: OEV comes from honest price updates, while manipulation involves distorting the data itself, but poorly designed capture systems could create new manipulation incentives. Measurement is also difficult, so estimates of how much value is at stake vary widely and should be treated with caution.