The DeFi Risk Taxonomy

01 · Concept — what problem does it solve?

DeFi yield is never free; it is payment for bearing a stack of risks, and most blowups happen because someone counted the yield and not the risks. This page is the field guide — the named categories of how money is lost on chain — and a pointer to the topic that covers each in depth. Internalize the taxonomy and most "how did this happen?" headlines become "of course: that's category N."

02 · Mechanics — the risk classes

• Smart-contract risk: a bug in immutable code holding funds. Mitigations: audits, formal verification, immutability, bug bounties. (Euler $197M, 2023.)
• Oracle risk: acting on a manipulated or stale price. The root of most "hacks." See Oracles.
• Liquidation / market risk: collateral crashing faster than liquidations can clear, leaving bad debt; cascades amplify it.
• Bridge / cross-chain risk: the most-exploited category by far — forged messages, compromised validators. See Bridges.
• MEV risk: value extracted by transaction ordering — sandwiches, front-running. See MEV.
• Governance risk: vote capture or a malicious proposal draining a treasury. (Beanstalk $182M.)
• Peg / depeg risk: stablecoins and LSTs trading away from par. (UST collapse.)
• Counterparty / custody risk: trusting an issuer, custodian, or CEX (USDC/SVB; FTX).
• Composability risk: inherited failure — a vault is only as safe as the riskiest thing it touches.

03 · Formulas

// stacked protocols multiply failure probability
P(loss) ≈ 1 − Π (1 − pᵢ)        over every layer i in the position

// the only honest yield comparison
real_yield = quoted_APY − expected_loss_from_all_risk_classes

04 · Edge cases & risks

• Correlation is the killer: risks that look independent fire together in a crisis — a crash triggers liquidations and a depeg and an oracle lag and a liquidity flight at once.
• Tail risk hides in steady yield: selling insurance (options, pegs, basis trades) looks like free money until the one event that pays out erases years of premium.
• "Audited" is necessary, not sufficient: every major exploit's protocol was audited. Audits reduce smart-contract risk; they say nothing about oracle, governance, or composability risk.
• The meta-risk: believing you've eliminated risk. In DeFi you relocate and re-price it — never delete it. Map it, size it, and never count yield without it.