DeFi Explained: What Is Decentralised Finance and How Does It Work?

Decentralised Finance — DeFi — is a system of financial services built on public blockchains, primarily Ethereum, that operates without banks, brokers, or any centralised intermediary. Instead of a bank holding your deposits and a broker executing your trades, software running on a blockchain does both, governed by code rather than a company. As of mid-2026, approximately $95 billion in crypto assets are locked in DeFi protocols globally.

How DeFi Replaces Traditional Institutions

Traditional banking works by pooling deposits, lending them out at higher rates, and keeping the spread. Traditional brokerage works by matching buyers and sellers and taking a fee. Both require trusted intermediaries who hold your assets and make decisions about what to do with them. DeFi replaces both functions with smart contracts — self-executing programmes that automatically execute the same functions when specific conditions are met.

A DeFi lending protocol like Aave or Compound holds no assets itself. It runs code on the Ethereum blockchain that automatically accepts deposits, calculates interest rates based on supply and demand, and processes loans and repayments without any human involvement or company decision-making. The code is publicly visible, auditable by anyone, and cannot be changed without consensus from token holders.

What DeFi Can Do That Banks Cannot

DeFi protocols operate 24 hours a day, seven days a week, with no minimum account balances, no identity verification, and no geographic restrictions. A £50 deposit earns the same annual yield rate as a £50 million deposit. Access requires only an Ethereum wallet and internet connection.

Yields in DeFi have historically exceeded traditional savings rates by significant margins. During 2021’s bull market, stablecoin yields on DeFi protocols regularly exceeded 10-20% annually. In mid-2026, yields on stablecoin deposits in established protocols like Aave on Ethereum mainnet are approximately 4-7% — still above most UK savings accounts.

The Major DeFi Risk Categories

Smart contract risk is fundamental: if the code contains a flaw, attackers can exploit it. DeFi protocols have lost over $6 billion to smart contract exploits since 2020. The Euler Finance hack in March 2023 resulted in $197 million in losses in a single transaction. Even audited protocols with security firms’ sign-off have been successfully exploited.

Liquidation risk applies to borrowing: DeFi loans are overcollateralised, meaning you must deposit more crypto than you borrow. If your collateral value drops below a threshold, it is automatically liquidated to repay the loan. During rapid price drops, cascading liquidations can occur. Anyone who borrowed against crypto collateral during the May 2021 or June 2022 crashes and was not monitoring positions faced automatic liquidation.

Oracle risk: DeFi protocols depend on price feeds called oracles to know what assets are worth. Oracle manipulation has been the attack vector for several significant DeFi exploits. When an attacker can convince a protocol that an asset is worth far more than it is, they can borrow against fake value. The bZx protocol was exploited this way for $8 million in 2020.

UK Regulatory Status of DeFi

DeFi is largely unregulated in the UK. The FCA’s crypto asset registration requirements apply to centralised crypto exchanges and custodians — entities with a UK nexus that hold customer assets. Fully decentralised protocols that run on a blockchain with no central operator are not captured by current FCA registration requirements.

This is changing. The FCA’s discussion paper DP23/4 on DeFi, published in 2023, signalled that the regulator is developing a framework for decentralised systems. The UK Financial Services and Markets Act 2023 granted the Treasury powers to regulate crypto assets broadly, including DeFi. Specific DeFi regulations are expected to be consulted on during 2026-2027. UK DeFi users have no FSCS protection and no recourse if a protocol is exploited or funds are lost.

Getting Started Safely

For UK investors considering DeFi, the practical starting points are the largest, most battle-tested protocols on Ethereum mainnet: Uniswap for decentralised exchange, Aave and Compound for lending, and Lido for liquid staking. These protocols have been running for years, have the largest security bounties, and have generally survived multiple market cycles without catastrophic failure.

Start with amounts you can afford to lose entirely. Use only non-custodial wallets you control — MetaMask, Rainbow, or a hardware wallet for larger amounts. Verify contract addresses independently before interacting. Never connect your wallet to a site found in a search ad result — phishing sites mimicking DeFi protocols are the most common attack vector for retail DeFi users.

What This Means for You

DeFi represents a genuinely different financial architecture — more transparent, more accessible, and operating on different risk parameters than traditional finance. The absence of an intermediary is simultaneously DeFi’s core value proposition and its primary risk. There is no Barclays to call when an Ethereum smart contract is exploited. Understanding both dimensions is the minimum requirement for participating with open eyes.

This article is for educational purposes only and does not constitute financial advice. Cryptocurrency investments involve significant risk. Always do your own research.