DeFi
Decentralised finance (DeFi) is the set of financial services — lending and borrowing, trading, derivatives, asset management, stablecoin issuance — operated by smart contracts on public blockchains rather than by licensed intermediaries: users interact with code that holds collateral, matches trades and enforces terms, governed by token holders and open to anyone with a wallet. It reached tens of billions of dollars of deposited value, suffered hacks and collapses that cost billions, and is partly absorbed into regulated finance.
- Also known as
- Decentralised finance, Decentralized finance, DeFi protocols, On-chain finance
- Used at
- over-collateralised lending (Aave, Compound: deposit crypto, borrow against it, with automatic liquidation); decentralised exchanges (Uniswap and the automated market makers: liquidity pools priced by formula); stablecoins issued against collateral (MakerDAO/Sky); derivatives and perpetual futures; yield aggregation; and, increasingly, tokenised real-world assets (treasuries, private credit) as collateral
- Binding
- contested — the EU's MiCA exempts "fully decentralised" services with no intermediary but regulates anyone who provides a service around them; the US SEC and CFTC have brought cases against protocol developers and front-end operators, and 2025 legislation set a stablecoin regime while market-structure rules remained in progress; AML authorities apply the travel rule and sanctions (the Tornado Cash sanctions and their partial reversal) to what they can reach; FATF guidance treats those with control or influence over a protocol as service providers
- Typical numbers
- total value locked peaked near $180 billion in late 2021, fell below $40 billion in 2022, and recovered above $100 billion in 2024–2025; hacks and exploits took over $3 billion in 2022 and more than $2 billion in 2024; stablecoins on-chain exceeded $200 billion in 2025, most of it in centrally issued tokens used across DeFi
- Typical risks
- smart-contract bugs and exploits (code holds the money; a flaw is a theft), oracle manipulation (the price feed a contract trusts is attacked), liquidation cascades, governance capture, the collapse of collateral (Terra/Luna, 2022), and the absence of recourse — no operator to reverse, refund or answer a complaint
- Parties
- protocol developers and their foundations, token-holder governance, liquidity providers, users, the front-end operators, the auditors of smart contracts, the regulators, and the institutions that began using permissioned versions of DeFi mechanisms for tokenised assets
How DeFi works in practice
A user deposits $100,000 of ether into a lending protocol's smart contract and borrows $60,000 of a dollar stablecoin against it. No one approved the loan: the contract's code accepts collateral of the right type, applies a loan-to-value limit, charges an interest rate set by a formula on the pool's utilisation, and, if the collateral's value (read from a price oracle) falls below the threshold, allows anyone to repay the debt and take the collateral at a discount — liquidation, automated and instant. The user repays when they choose; the lenders who deposited the stablecoins earn the interest, less a protocol fee that token holders voted on. A trade on a decentralised exchange is similar: a pool holds two assets, a formula sets the price, the trade executes against the pool, and liquidity providers earn the fee. The mechanisms are transparent, permissionless and unstoppable — including by anyone who would like to stop a theft.
The consequences define the sector's relation to regulated finance. The mechanisms work — automated collateral management and liquidation, transparent pools, composable contracts — and institutions have adopted them on permissioned chains for tokenised assets, where the participants are known and the recourse exists. The public protocols carry the risks the mechanisms cannot remove: code exploits, oracle attacks, collateral collapses, and the anonymity that makes them a venue for laundering and sanctions evasion. Regulators have reached the intermediaries around them — exchanges, front-ends, developers with control, stablecoin issuers — and left the pure protocol contested. For a fintech, DeFi is a source of mechanisms worth studying and a counterparty risk to manage: customers who move funds to it, stablecoins that depend on it, and yields advertised from it. For a buyer, a DeFi-adjacent target is diligenced on which of its activities a regulator would attribute to it and on the smart-contract audits behind what it runs.
For a fintech founder, DeFi's contribution is a set of financial primitives that run as code; its warning is what happens to money that code holds when the code is wrong; and its regulatory status is the question every product that touches it must answer.
Example
A crypto-asset service provider licensed under MiCA offers customers a "yield" product that deposits their stablecoins into a lending protocol, paying 6% against the protocol's 8%. Diligence by a prospective acquirer in 2025: the product makes the provider the intermediary the regulation reaches — it must treat the yield as a service it provides, with the protocol's smart-contract risk as its own; the protocol's last audit was eighteen months old and a governance vote had since changed the collateral parameters; and the provider had no reserve against an exploit. The acquirer's conditions: the product is suspended until the smart-contract exposure is re-audited and a capital buffer is held against it, the product's disclosures are rewritten to describe the risk as the provider's own, and the regulator is informed. The price is reduced by the buffer required; the founders accept, having been told by the acquirer's counsel what the regulator would have said next year.
Common mistakes
- Reading "decentralised" as "unregulated"; the intermediaries around a protocol are reached. - Offering customers a DeFi yield without owning the smart-contract risk behind it. - Trusting an audit as a guarantee; code changes and exploits are found afterwards. - Collateral that depends on the price of the token issued against it. - Forgetting that in DeFi there is no one to call when the money is gone.