What is DeFi insurance and how does it work?

DeFi insurance is protection you buy on a blockchain against specific crypto losses, such as a hack of a lending protocol. Members, not an insurance company, put up capital and share the risk. It exists because government schemes like the FDIC do not cover crypto, as explained in is crypto insured.

How does DeFi insurance work?

Nexus Mutual is the best-known example. Its website says it has offered cover since 2019 and ranks first in claims paid. Its documentation describes a decentralized insurance alternative built on Ethereum.

The flow works like this:

• Buy cover. You pick a product, an amount and a cover period. Fees can be paid in ETH, USDC, cbBTC or NXM, the mutual's token.
• Capital backs it. Half of each fee goes to NXM holders who stake to underwrite that risk, and half to the capital pool backing all NXM, the FAQ says.
• File a claim. If a covered event hits you, you submit a claim with a 0.05 ETH deposit, which is returned if the claim is accepted and forfeited if it is denied.
• Assessment. A claims committee reviews the claim, voting runs for up to 72 hours, a 24-hour cooldown follows, and an accepted payout must be redeemed within 30 days.

To join, Nexus Mutual requires an identity check with government ID and a one-time 0.0020 ETH fee. It cannot accept members from 27 listed countries, including China, India and Japan.

What is smart contract cover?

Smart contract cover pays when a covered protocol is exploited and you lose funds held in it. Nexus Mutual's site lists smart contract hacks, custody failure, slashing and depegs among the risks it covers. Each product has its own cover wording that sets out what is covered, what is excluded and what counts as a loss.

The Euler Finance exploit shows how it plays out. On March 13, 2023, Euler lost $197 million. Nexus Mutual paid 10 claims worth about $3.39 million and denied one. The mutual later asked claimants to return their payouts, and its records show nearly all of the DAI but less than half of the ETH came back. Cover is a backstop, not a replacement for checking a protocol, including whether it had a smart contract audit.

Is DeFi insurance real insurance?

Not in the legal sense. Nexus Mutual's FAQ states plainly that its cover is not a contract of insurance. It calls itself a discretionary mutual, where cover is provided on a discretionary basis and members have the final say on which claims are paid. There is no legal duty to pay as there would be with a licensed insurer.

You rely on the mutual's design, capital and claim assessors. Nexus Mutual says members had paid more than $18.5 million for losses from exploits, failures and custodian halts as of August 2026, and its site lists payouts after FTX, Rari Capital and Euler.

The apps this cover protects are explained in what is DeFi. Cover helps only for the events its wording names, and only if members approve the claim.