Understanding DeFi: How Decentralized Finance Replaces Banks

Decentralized finance (DeFi) attempts to replace banks by rebuilding their functions, such as lending, exchanging and moving money, as open-source programs on a public blockchain. It replicates those functions well enough to be used by anyone with a wallet, but it does not replicate the protections that surround them in a regulated bank: deposit insurance, legal limits on losses from unauthorized transfers, a human decision-maker and a central bank behind the system. So DeFi is better described as a different bundle of functions and risks than as a one-for-one replacement.

Key takeaways

DeFi swaps a loan officer, a market maker and a custodian for smart contracts, formulas and private keys. The functions carry over; the protections do not.
The FDIC insures deposits up to $250,000 per depositor, per insured bank, per ownership category, and its guidance lists crypto assets as not covered.
DeFi loans are over-collateralized and liquidated automatically: in the illustrative example below, a 16.7 percent fall in the collateral's price is enough to open part or all of the loan to liquidation, with no negotiation.
The World Bank's latest confirmed global average cost of sending $200 abroad is 6.36 percent (third quarter of 2025, the latest issue found as of October 2026), which is the gap on-chain payments try to close, though they add their own conversion and security costs.
The BIS argues that full decentralization is an illusion, because governance needs make some centralization inevitable, and that DeFi has no shock absorbers in a crisis.

What banks bundle and DeFi splits

A bank sells two things as one product. The first is a set of functions: somewhere to keep money, credit, currency exchange and payment rails. The second is a set of protections that most customers only notice when something fails.

In the United States the best known protection is deposit insurance. The FDIC covers deposits up to $250,000 per depositor, per insured bank, for each account ownership category. It does not cover investments, and it does not cover crypto assets or the failure of an institution that is not an FDIC-insured bank.

Other protections are legal rather than insurance-based. Under Regulation E, section 1005.6, a consumer's liability for unauthorized electronic fund transfers from an account is limited in tiers: no more than $50 if a lost or stolen card or other access device is reported within two business days of learning of it, up to $500 if reported later, and potentially unlimited if the consumer does not report an unauthorized transfer shown on a statement within 60 days of the statement being sent, for later transfers that timely notice would have stopped. The rule covers unauthorized transfers only, not payments the account holder authorizes, including payments a scammer talks someone into making.

DeFi works differently. Its services are smart contracts, programs on a blockchain that hold funds and follow fixed public rules. A user reaches them through a wallet, which is a pair of cryptographic keys instead of an account at an institution; whoever controls the keys controls the money. Rules in public code and control by private key are what remove the intermediary, and they are also what remove the intermediary's protections.

Function-by-function comparison

Function	How a bank does it	DeFi mechanism	Protection that does not carry over
Lending	Credit officer underwrites; terms can be renegotiated	Over-collateralized smart-contract loans	Human judgment, forbearance, workout
Trading	Market makers quote prices	Automated market maker pools	A broker's best-execution duty
Custody	Bank holds funds and can restore access	Self-custody with private keys	Account recovery, deposit insurance
Payments	Card and bank transfers with dispute channels	On-chain transfers, often in stablecoins	Liability limits and disputes for unauthorized transfers
Crisis backstop	Deposit insurance, central bank liquidity	Collateral posted by borrowers	Emergency liquidity

The Bank for International Settlements (BIS) makes the last row's point in its December 2021 Quarterly Review article on DeFi: DeFi relies on private backstops such as collateral, and in its words "there are no shock absorbers in DeFi that can cut in during stress periods." Banks can expand their balance sheets under stress because they have access to central bank balance sheets; DeFi protocols do not.

Lending without a loan officer

Protocols such as Aave replace underwriting with collateral. A borrower does not submit an application or income documents. Instead the borrower deposits crypto worth more than the loan, and the contract lends against it. The BIS notes that DeFi lending tends to be over-collateralized, and that loans are liquidated automatically when the collateral ratio falls below a threshold.

Aave's documentation defines a health factor: the collateral value multiplied by a liquidation threshold, divided by the borrowed value. Once it drops below 1, the position can be liquidated.

Health factor = (collateral value x liquidation threshold) / borrowed value
Collateral value at liquidation = borrowed value / liquidation threshold

Illustrative example. Assume a liquidation threshold of 80 percent (parameters differ by asset and protocol, so this is a round number, not a quote). A borrower deposits $150 of crypto and borrows $100 in a stablecoin.

Starting health factor: ($150 x 0.80) / $100 = 1.2.
The position can be liquidated once collateral falls below $100 / 0.80 = $125.
That is a $25 drop, or 16.7 percent of the $150 deposited. The more volatile the collateral, the sooner a fall of that size can arrive.

A bank loan officer might call, extend a deadline or restructure. The contract has no such discretion. The borrower can repay or add collateral to lift the health factor, but once it is below 1 any liquidator can act at any moment. Two conditions the example leaves out also push the health factor down: interest accrues on the debt, so it drifts lower even if prices hold steady, and if the borrowed asset is itself volatile, a rise in its price has the same effect as a fall in the collateral.

Markets run by a formula

On a traditional exchange, professional market makers stand ready to buy and sell. DeFi exchanges such as Uniswap use an automated market maker: a pool holding two tokens, priced by a rule. Uniswap's documentation describes the constant product formula, x * y = k, where x and y are the reserves of each token and k must stay constant or grow after every trade. Anyone can deposit a token pair and become a liquidity provider, and swap fees accrue to those providers.

The protection missing here is the duty a regulated broker owes its customer. Under FINRA Rule 5310, a broker-dealer must use reasonable diligence to find the best market for a customer's order; a pool simply applies its formula to whoever trades with it. A liquidity provider takes on impermanent loss: the shortfall compared with simply holding the same tokens. Uniswap's v2 documentation, which covers pools that spread liquidity across all prices, gives the formula, where price ratio is the price now divided by the price when liquidity was added:

Impermanent loss = 2 x sqrt(price ratio) / (1 + price ratio) - 1

Illustrative example. A provider deposits $500 of ETH (0.5 ETH at $1,000) and $500 of a stablecoin into a pool, and ETH then doubles to $2,000.

The pool constant is k = 0.5 x 500 = 250. At a $2,000 price the pool rebalances to about 0.354 ETH and $707.
The position is worth about $707 + $707 = $1,414.
Simply holding would be worth 0.5 x $2,000 + $500 = $1,500.
The shortfall is about $86, or 5.7 percent, matching Uniswap's published figure for a 2x move. The example ignores swap fees, which may or may not offset the shortfall.

Custody, payments, no backstop

Custody becomes the user's job

A bank is accountable for holding deposits. In DeFi, funds sit at an address controlled by a key, and there is no branch or fraud department to call if the key is lost or a malicious transaction is signed. Key handling and transaction approval become the user's own safety system. Custodial and non-custodial wallets differ in who holds the keys, and that difference decides who carries this risk.

Payments that cannot be recalled

This is where on-chain payments aim to compete on cost. The World Bank's Remittance Prices Worldwide database reports that sending $200 internationally cost a global average of 6.36 percent in the third quarter of 2025, the latest issue confirmed for this article as of October 2026; digital services averaged 4.59 percent. The World Bank's report for that quarter (Issue 54) notes that the UN Sustainable Development Goals and the G20 set a 3 percent target for the global average by 2030.

Rate on a $200 transfer	Fee in dollars
Global average, 6.36 percent	$12.72
Digital services average, 4.59 percent	$9.18
UN and G20 2030 target, 3 percent	$6.00

The saving on-chain is not guaranteed to be the whole gap. Network fees vary, and the sender and recipient usually still need to convert cash to and from a stablecoin, which can carry its own fees and exchange-rate costs.

The trade-off is finality. A transfer signed with a stolen key is, in bank terms, an unauthorized transfer, but no Regulation E liability limit or dispute process applies on-chain, and a payment to a mistyped address has no institution to ask for help. Authorized payments to a scammer are hard to recover in either system.

No lender of last resort

When a bank is in trouble, a central bank can lend against its assets and insurance caps depositor losses. Over-collateralization protects an individual loan, but DeFi has no backstop of its own for the system when confidence disappears at once, and it is still exposed to banks through stablecoin reserves.

A Federal Reserve note on stablecoin markets (February 2024) records that Terra, the largest algorithmic stablecoin before its collapse, failed in May 2022. It also records that in March 2023, after Circle said it could not wire out part of USDC's reserves held at Silicon Valley Bank, USDC and DAI, which is partly collateralized by USDC, fell to lows under 90 cents before recovering over about three days. Circle said USDC liquidity operations would resume when banks opened on Monday, a reminder that round-the-clock blockchains still meet bank hours at the cash edge.

Where DeFi does better

DeFi has real strengths. It is permissionless: the World Bank's Global Findex 2025 reports that 79 percent of adults worldwide have an account, which leaves roughly one in five without one, and a wallet does not ask for permission. Balances and code are public and auditable, services can be combined, and settlement runs around the clock.

Those advantages come with limits. The BIS argues that full decentralization in DeFi is illusory, because some centralized governance is needed to take strategic and operational decisions. Where a protocol keeps upgrade or admin controls, a rule change by a small group or a compromised key can alter the code a user relied on.

Frequently asked questions

Does FDIC insurance cover money held in DeFi or crypto?

No. The FDIC lists crypto assets among the products it does not insure, and it states that non-deposit investment products are not covered even when an FDIC-insured bank offers them. Coverage also applies only if the bank itself is FDIC-insured, which the FDIC suggests checking with its BankFind Suite tool; the default or bankruptcy of a company that is not an insured bank is not covered.

Who triggers a liquidation on a lending protocol?

Aave's help page says liquidations are permissionless, meaning any network participant can start one, and that successful liquidations often need custom-coded bots. A liquidator repays part of the debt and receives collateral worth that amount plus a liquidation bonus taken from the borrower's collateral. As the page reads in October 2026, up to 50 percent of the debt can be liquidated when the health factor is above 0.95 and both collateral and debt are at least $2,000, and up to 100 percent when the health factor is 0.95 or lower or either amount is under $2,000. These parameters can change between protocol versions.

Does impermanent loss only happen when the price rises?

No. Uniswap's documentation states that the loss is the same whichever direction the price moves, so a halving costs a provider the same share as a doubling. The loss shrinks to zero if the price returns to its starting level, which is why it is called impermanent, but it becomes a realized loss if the provider withdraws first.

Can DeFi reach the 1.3 billion adults without financial access?

It could reach some of them, but a wallet still needs a device and a connection. The World Bank reports that about 1.3 billion adults still lack access to financial services. Those users would also carry the custody and price risks described above, so access to a wallet does not make DeFi suitable for them.

Is DeFi actually free of intermediaries?

Not entirely. The BIS argues that governance decisions are unavoidable and that proof-of-stake consensus tends to concentrate power in large coin-holders. A protocol's behavior can therefore still depend on developers, governance token holders and validators, and a user has to check who holds that influence.

A checklist before using DeFi

The practical question is which job each tool should do. A reasonable test for any DeFi use is to name the protection being given up and decide who now covers it.

Keep insured cash separate. Emergency savings and money needed soon belong where FDIC coverage applies; crypto assets are outside it.
Treat every payment and signature as final. Check the address, send a small test amount first, and review what a transaction approves before signing.
Check the liquidation math before borrowing. Work out the collateral price at which the position can be liquidated, as in the example above, allow for interest building up on the debt, and keep a wide margin.
Find out who can change the rules. Look for admin keys, upgradeable contracts and how governance works before depositing.
Size positions to survive a total loss. With no backstop, the amount at risk is whatever the reader is willing to lose entirely.