How Crypto Lending Works

What Is Crypto Lending?

Crypto lending is the act of supplying digital assets to a borrower in exchange for interest payments. The lender earns yield on idle assets; the borrower gains liquidity without selling their holdings. Three distinct markets have emerged to serve this demand — exchange margin, institutional OTC desks, and on-chain DeFi protocols — each with fundamentally different mechanics, counterparty structures, and risk profiles.

The crypto lending market grew to an estimated $64 billion in outstanding loans at its 2021 peak, fuelled by bull-market leverage demand and yield-hungry institutions. The 2022 bear market triggered a cascade of failures — Celsius, BlockFi, Voyager, Genesis — that collectively destroyed tens of billions in lender capital and wiped out almost every major centralised lending platform. What survived — and what has since grown — is primarily DeFi lending, where smart contracts enforce collateral requirements without trusting any human counterparty.

Understanding where and how to lend or borrow requires understanding all three venues. Exchange margin lending is the most accessible but bundles your capital with the exchange's counterparty risk. OTC institutional lending offers flexibility and scale but requires large minimums and careful legal structuring. DeFi protocols are transparent and non-custodial but replace counterparty risk with smart contract and oracle risk.

Exchange & Margin Lending

Exchange lending takes two forms: margin lending, where retail users lend their assets to other users borrowing to take leveraged positions, and earn products, where the exchange pools deposits and deploys them to earn yield. Both expose the lender to the exchange as a counterparty — not just to the end borrower.

In a margin lending order book (used by Bitfinex and some Binance products), lenders submit offers specifying an interest rate and term. Borrowers needing leverage to trade match against these offers. When a borrower opens a margin position, the platform automatically draws on the lending pool at the clearing rate. The exchange acts as an intermediary, enforcing margin requirements and liquidating positions before they become undercollateralised — but if the liquidation fails (a gap down, a platform outage), the lender bears the loss.

Exchange earn products are simpler but more opaque. Platforms like Binance Earn, Bybit Earn, and OKX Earn accept deposits and promise a fixed or variable APY. The exchange deploys these funds — sometimes to fund its own margin book, sometimes into DeFi protocols, sometimes into undisclosed counterparties. FTX's collapse in November 2022 demonstrated the terminal risk: earn product deposits were used to fund undisclosed loans to FTX's affiliated trading firm Alameda Research. When Alameda became insolvent, earn depositors lost everything.

The key structural issue with exchange lending is asset co-mingling. Unless an exchange explicitly segregates lender deposits (almost none do), your capital sits alongside user trading balances in the exchange's omnibus accounts. In insolvency, you become an unsecured creditor — as BlockFi depositors discovered in 2022. Regulated exchanges (Coinbase in the US, Coinbase Institutional for qualified investors) offer better protections, but even these are not equivalent to direct lending with a perfected security interest in collateral.

OTC & Institutional Lending

Over-the-counter (OTC) crypto lending is bilateral: a lender and a borrower negotiate terms directly (or through a desk) and sign a loan agreement before any capital moves. This structure offers the most flexibility but demands legal sophistication, large minimums, and careful diligence on the counterparty.

The typical OTC crypto loan involves three parties: the lender (institution, fund, family office), the borrower (crypto fund, miner, market maker, corporate treasury), and a custodian (BitGo, Copper, Anchorage, Fireblocks) that holds the collateral in a segregated account. The loan agreement specifies the loan amount, currency, interest rate, loan-to-value ratio, margin call thresholds, cure period, and liquidation procedures. Unlike exchange margin, nothing is automatic — everything is contractual.

Rehypothecation is the defining risk factor in OTC lending. A lender who re-lends your collateral to a third party is using your assets to generate additional yield — but if that third party defaults, your collateral may be encumbered or lost. The Genesis collapse occurred in part because Genesis re-lent client collateral (including assets posted by Three Arrows Capital) without clients' explicit understanding of the terms. Negotiating an explicit prohibition on rehypothecation — or demanding segregated custody at a third-party custodian — is essential for large OTC loans.

OTC lending rates are privately negotiated and never publicly disclosed. Indicative rates depend on the borrower's credit quality, the collateral type and haircut, the loan term, and current supply-demand for the specific asset. During the 2021 bull market, prime borrowers paid 6–10% for BTC-collateralised USD loans; less creditworthy borrowers or those borrowing specific altcoins paid multiples of that. The OTC market effectively has no public price discovery — rates are what two parties can agree on.

The borrower profile for OTC lending is specific: crypto miners who hold BTC reserves and need USD to fund operations; crypto hedge funds using leverage without selling their core positions; market makers who need to borrow specific tokens to settle short positions or fulfil client orders; and corporate treasuries seeking USD liquidity against crypto balance sheets. Retail investors have no access — minimums typically start at $1–5 million.

DeFi Lending Protocols

DeFi lending protocols are smart contracts that match lenders and borrowers automatically, with interest rates set by an on-chain algorithm based on utilisation. No counterparty risk, no credit checks, no custody — but also no safety net if the smart contract has a bug.

The dominant design is the pooled lending model, pioneered by Compound and extended by Aave. Lenders deposit assets into a shared pool and receive a receipt token (aTokens for Aave, cTokens for Compound) representing their proportional share of the pool plus accrued interest. Borrowers post collateral and borrow from the pool up to their borrowing capacity — limited by the collateral's loan-to-value (LTV) ratio set by protocol governance.

The protocol enforces overcollateralisation at all times. A borrower who posts $100 of ETH at a 75% LTV can borrow up to $75 in stablecoins. If the ETH price falls, the LTV rises — and when it breaches the liquidation threshold (e.g., 82.5% for ETH on Aave v3), the position is eligible for liquidation. There is no margin call notice, no cure period, and no negotiation. Any address can trigger the liquidation and collect the liquidation bonus.

The two most important properties of DeFi lending are non-custody and permissionlessness. The protocol smart contracts hold the collateral, not a company. No single entity can freeze deposits, misappropriate funds, or selectively deny access. Aave V3 had over $10 billion in active loans at its peak — all managed without a credit department, a legal team, or a compliance officer.

The trade-off for non-custody is smart contract risk. Euler Finance — a highly audited DeFi lending protocol — was exploited for $200 million in March 2023 via a donation/liquidation attack that exploited a flaw in the protocol's collateral accounting. The funds were ultimately returned by the attacker (an unusual outcome), but the exploit demonstrated that even sophisticated, multi-audited protocols can fail in unexpected ways.

How Interest Rates Are Set

The three venues set interest rates by entirely different mechanisms — order-book matching, bilateral negotiation, or algorithmic utilisation curves — producing rates that diverge significantly across market conditions.

DeFi interest rates are determined by a two-slope utilisation model. At low utilisation (below the "kink"), rates increase gradually as more of a pool is borrowed — nudging lenders to supply more. At the kink (typically 80% utilisation for stablecoins), the slope steepens dramatically. If utilisation reaches 100%, the borrow rate can exceed 100% APY — a signal to borrowers to repay and lenders to supply. The formula is:

borrowRate = baseRate + (utilisation / kink) × slope1 below the kink, and a much steeper slope2 component above it. The supply rate is derived from the borrow rate: supplyRate = borrowRate × utilisation × (1 − reserveFactor). The reserve factor is the protocol's take — typically 10–20% — which flows to the treasury.

Exchange margin rates on platforms like Bitfinex are set by a lending order book: lenders post offers at a specific daily rate, borrowers take the cheapest available rate. During the 2021 bull run, USDT margin funding on Bitfinex hit 0.1% per day — equivalent to 36.5% APY — sustained for weeks as perpetual traders paid enormous sums to maintain leveraged longs. During bear markets, the same funding rate falls to 0.01–0.02% per day as demand collapses.

Collateral & Liquidations

All three lending venues use collateral to protect lenders from borrower default, but the mechanisms — how collateral is held, how liquidations are triggered, and who executes them — are radically different.

In DeFi, collateral is held by the smart contract itself. A borrower's health factor is calculated continuously: health factor = (collateral value × liquidation threshold) / debt value. When it falls below 1.0, any address can submit a liquidation transaction — repaying up to 50% of the debt in exchange for that value of collateral plus a bonus (typically 5–15% depending on the asset). MEV bots scan the mempool and each new block for sub-1.0 health factors, competing to be the first to submit the liquidation.

Exchange liquidations are automated but centralised. The exchange's liquidation engine monitors all margin accounts and sells collateral when maintenance margin is breached. During extreme volatility — the 3,000-point Bitcoin drop on 12 March 2020 and the May 2021 crash — exchange liquidation engines were overwhelmed, orders queued, and positions were closed at prices far below the trigger level. Some exchanges use an auto-deleveraging (ADL) mechanism that closes profitable positions of winning traders to cover losses — a socialised-loss mechanism that surprises traders who discover their profitable positions have been unwound.

OTC liquidations are governed by loan agreements. The standard process involves a margin call notice when LTV breaches the first threshold, a cure period (typically 24–72 hours) during which the borrower can top up collateral or repay, and then — if uncured — the lender or a designated liquidation agent sells the collateral. This controlled process failed spectacularly during the 2022 crash: Three Arrows Capital (3AC), which had borrowed from dozens of OTC lenders, defaulted on $3.5 billion in loans in June 2022. The collateral — which included large GBTC positions trading at a discount to NAV — was insufficient to cover the loans, leaving lenders (Genesis, BlockFi, Voyager) with uncovered losses that cascaded into their own insolvencies.

Undercollateralised Lending

The primary limitation of DeFi lending is that it requires overcollateralisation — you must post more value than you borrow. This makes DeFi useless for the most common lending use case in traditional finance: borrowing against future cash flows or reputation. Several protocols have attempted to solve this, with limited success.

Maple Finance and Clearpool use an institutional credit model: institutional borrowers (market makers, trading firms) establish on-chain credit pools, publish their identity and financial information, and borrow from retail/institutional lenders without posting full collateral. Lenders assess creditworthiness manually — the protocol handles disbursement and repayment but cannot enforce collateral recovery if the borrower defaults. Maple lost approximately $50 million in the 3AC/Orthogonal Trading collapse of 2022, demonstrating that undercollateralised on-chain lending inherits all the credit risk of traditional lending with fewer enforcement tools.

Goldfinch attempts real-world undercollateralised lending to businesses in emerging markets, using a two-tier model: backers (risk-tolerant capital) absorb first losses, while senior liquidity providers earn lower rates with seniority protection. The model has proven difficult to scale due to the challenge of on-chain credit assessment for off-chain borrowers, and default rates have been higher than anticipated.

Flash loans are a uniquely DeFi form of uncollateralised lending that bypasses the credit problem entirely. A flash loan is borrowed and repaid within a single transaction block — if the repayment fails, the entire transaction reverts as if it never happened. This atomicity means the protocol faces zero credit risk regardless of the loan size. Flash loans are used for arbitrage, liquidations, collateral swaps, and — in the hands of attackers — to amplify oracle manipulation exploits.

Major Players

The crypto lending landscape was reshaped by the 2022 crash. Most centralised lenders collapsed; the survivors are concentrated among regulated institutions and DeFi protocols that survived without a human counterparty.

The common thread in the 2022 collapses was undisclosed rehypothecation combined with concentrated counterparty exposure. Each collapsed lender had taken user deposits, re-lent them to a small number of large counterparties (3AC, Alameda, Luna ecosystem projects), and had no contractual protection when those counterparties defaulted simultaneously. DeFi protocols that survived — Aave, Compound, Curve — did so because their collateral requirements are enforced by code, not agreements.

Regulatory Landscape

Crypto lending sits at a difficult regulatory intersection: it looks like banking (taking deposits, making loans) and sometimes like securities (interest-bearing accounts may be securities), but fits neither category cleanly. Regulators globally have taken inconsistent approaches, with the US being the most aggressive enforcer.

In the United States, the SEC has taken the position that certain crypto lending products are securities. BlockFi settled with the SEC in February 2022 for $100 million over its BlockFi Interest Accounts — the SEC's position was that offering fixed yields on crypto deposits constituted offering unregistered securities. Celsius and Gemini Earn faced similar actions. Coinbase proposed a lending product in 2021 and received an SEC Wells notice before it launched, ultimately shelving the product.

For DeFi protocols, the primary regulatory uncertainty is whether the protocol itself — or its front-end operators and governance token holders — constitute a regulated entity. The CFTC sued Ooki DAO in 2022, asserting that DAO token holders could be held personally liable as an unincorporated association. The SEC has not yet brought a case against a major DeFi lending protocol but has signalled it is watching governance structures closely. Aave and Compound have implemented geo-restrictions on certain front-end interfaces under legal pressure.

Internationally, the UK's Financial Conduct Authority (FCA) regulates cryptoasset promotions and has expressed concern about yield products marketed to retail investors. The EU's Markets in Crypto-Assets Regulation (MiCA), in force from 2024, does not directly address DeFi lending but imposes strict requirements on centralised crypto lending products as crypto-asset service providers (CASPs). Singapore's MAS has licensed several institutional crypto lenders under its Payment Services Act framework.

Risks

Crypto lending carries risks that do not exist in traditional lending markets: smart contract exploits, oracle manipulation, rehypothecation without disclosure, and the absence of deposit insurance. Understanding which risks apply to which venue — and whether they are hedgeable — is essential before committing capital.

For lenders, the dominant question is where your capital sits when you are not lending it. On an exchange, it sits in the exchange's omnibus accounts — earning nothing and subject to full counterparty risk. In a DeFi protocol, it sits in a smart contract earning supply interest continuously. In OTC, it either sits in your own custody or — more commonly — has already been deployed to a borrower with a contractual claim rather than actual possession.

For borrowers, the critical parameter is liquidation risk under stress. DeFi liquidations are instantaneous and ruthless — a 10% price move in a thin market at 3am can wipe a position before any human can respond. OTC cure periods feel generous until a market crashes 40% in 12 hours. Exchange systems fail during peak volatility, when you most need them to function. There is no venue where liquidation risk is truly manageable without active monitoring and conservative LTV ratios.