DeFi is a system of financial tools and services built on smart contracts on blockchain (mainly Ethereum), without the need for intermediaries like banks or exchanges. It enables lending, borrowing, speculation on asset prices (derivatives), cryptocurrency trading, risk insurance, and yields from savings. It's a layered architecture with high composability (composite blocks), but it brings high risks like code errors or hacks. DeFi protocols have varying degrees of decentralization – some are truly neutral, others are subject to manipulation or regulation like traditional finance.
History
DeFi originated in blockchain and fintech, with decentralized exchanges (DEX) as an alternative to traditional payments. Smart contracts spread with Ethereum in 2017. Key projects: MakerDAO (2017, lending stablecoin DAI, renamed to Sky in 2024 with USDS; circulating supply ~9 billion USD in March 2025). In June 2020, Compound launched yield farming, leading to a boom. By September 2020, DeFi accounted for 2/3 of crypto market price changes with 9 billion USD in collateral. Peak TVL (total locked value) 178 billion USD in November 2021, drop below 40 billion in 2023. Investors like Andreessen Horowitz poured in billions. In May 2025, Aave holds 45% of TVL (~25.4 billion USD).
How It Works
DeFi runs on decentralized applications (DApps) on blockchain, with transactions between users via smart contracts or open software. Access via wallets like MetaMask. DApps connect for complex services – e.g., stablecoins are lent into liquidity pools in protocols like Aave, where interest rates change based on demand. Oracles are used for external data (asset prices). Examples: flash loans (without collateral, repaid in one transaction), Uniswap (DEX with liquidity pools, where liquidity providers earn from fees without KYC).
Key components:
Smart contracts: Automate loans, trades.
DEX: Peer-to-peer or AMM (automated market maker) without intermediaries.
Lending protocols: Dynamic interest rates, e.g., MakerDAO for stablecoins.
Advantages
DEX reduce theft risk (no need to send assets to an exchange), offer anonymity without KYC. Average weekly trading volume on DEX in mid-2025: 18.6 billion USD, with 9.7 million unique wallets. Greater accessibility and higher yields.
Risks and Criticism
Code errors, hacks, and irreversible transactions are common. Anonymous founders can disappear with funds (rug pulls). In 2021, half of crypto crime was related to DeFi (129 million USD in hacks). Risks: complexity for users, impermanent loss (loss for liquidity providers), slippage, front-running. Decentralization isn't always real – upgradable contracts allow manipulation. Governance via DAO often concentrated in few hands. Regulation: SEC lawsuits (e.g., EtherDelta 2018), FATF recommendations from 2021.
Significant Events and Statistics
Bancor hack (2018): loss of 13.5 million USD.
TVL peak: 178 billion (2021), drop below 40 billion (2023).
DeFi scams: 129 million USD in 2021.
DEX volume: 18.6 billion weekly (2025).
Future
DeFi faces regulations (FATF 2021). The Economist (2022) sees a three-way battle between Big Tech, state digital currencies, and DeFi. Regulatory challenges in the US with 2.5 trillion USD in crypto. Future: potential for decentralized financing, but risks of scams and regulations.