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An Introduction to Under-Collateralized Lending Protocols

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An Introduction to Under-Collateralized Lending Protocols

A technical analysis of lending models that break the over-collateralization paradigm to enable efficient on-chain credit.
Chainscore © 2025

Foundational Concepts and Mechanisms

An overview of the core principles and operational models that enable lending without requiring borrowers to lock up assets of equal or greater value.

Credit Delegation

Credit Delegation allows a lender to delegate their borrowing capacity to a trusted third party. This mechanism separates the act of providing collateral from the act of taking on debt.

  • A user deposits stablecoins into a pool, granting a credit line to a specific, pre-approved borrower.
  • The borrower can then draw funds up to the delegated limit without posting their own collateral.
  • This enables capital efficiency for institutional players and introduces a web of trust, moving beyond pure algorithmic underwriting.

Identity & Reputation-Based Scoring

Identity & Reputation-Based Scoring uses on-chain and off-chain data to assess a borrower's creditworthiness without traditional collateral. It creates a financial identity tied to a wallet or entity.

  • Protocols analyze transaction history, DeFi activity, and even verified real-world credentials.
  • A high-score user might access a larger loan at a lower rate.
  • This is crucial for onboarding new users and businesses lacking substantial crypto assets but with strong operational histories.

Liquidity Pools & Tranches

Liquidity Pools & Tranches structure capital to manage risk for lenders. Funds are pooled, then split into senior and junior tranches with different risk/return profiles.

  • Senior tranches offer lower yields but are first in line for repayment, absorbing losses last.
  • Junior tranches take the first loss but earn higher yields.
  • This attracts both risk-averse and yield-seeking capital, creating a more robust and scalable lending market for under-collateralized loans.

Default Mechanisms & Guarantor Funds

Default Mechanisms & Guarantor Funds are safety nets that protect lenders when loans fail. They are capital reserves specifically set aside to cover losses from borrower defaults.

  • A portion of protocol fees or yields is automatically diverted to build this fund.
  • In a default, the guarantor fund repays lenders, preventing immediate loss.
  • This mechanism builds systemic trust and stability, making the protocol more resilient and attractive to conservative capital providers.

Overcollateralization to Under-collateralization Bridge

This Bridge describes the risk spectrum protocols use, often starting users with over-collateralized loans and gradually offering under-collateralized terms as trust is established.

  • A new user starts by borrowing 50% of their collateral's value (e.g., MakerDAO).
  • Through consistent repayment and on-chain history, they can access loans for 70%, 90%, or even 100%+ of collateral value.
  • This phased approach safely introduces under-collateralization, reducing risk for the protocol while building user credit history.

Architectural Models for Under-Collateralization

A technical process overview for implementing and interacting with under-collateralized lending protocols.

1

Protocol Selection and Risk Assessment

Choose a protocol and evaluate its risk parameters.

Detailed Instructions

Begin by selecting an under-collateralized lending protocol like Aave Arc, Maple Finance, or TrueFi. The core architectural decision hinges on the credit delegation model or pool-based underwriting. Before depositing funds, you must thoroughly assess the protocol's risk parameters and the creditworthiness of borrowers.

  • Sub-step 1: Analyze Whitelisted Entities: For permissioned pools (e.g., Maple), review the on-chain identity and historical performance of the Pool Delegates who underwrite loans. Check their default rates at addresses like 0x7C....
  • Sub-step 2: Review Loan-to-Value (LTV) Ratios: Unlike over-collateralized loans, these protocols may offer LTVs up to 100% or higher. Verify the specific LTV for your asset pair (e.g., USDC to a corporate borrower).
  • Sub-step 3: Examine Liquidation Mechanisms: Understand the liquidation waterfall and the role of first-loss capital. Determine who bears the initial default risk—often liquidity providers or junior tranche holders.

Tip: Use a blockchain explorer to audit the smart contract code of the Pool's Smart Contract (e.g., 0x4937...) for transparency on fund flows and default handling.

2

Capital Provision and Tranche Selection

Deposit funds into the appropriate risk tranche of the protocol.

Detailed Instructions

Under-collateralized protocols often use a capital stack or tranche system to separate risk. As a liquidity provider, you must choose between senior (lower yield, lower risk) and junior (higher yield, first-loss) tranches. This step involves locking your capital into a specific pool's smart contract.

  • Sub-step 1: Connect Wallet and Approve Token: Connect your Web3 wallet (e.g., MetaMask) to the protocol's UI. Approve the token (e.g., USDC) for spending by the pool contract. The approval transaction will specify a spender address like 0x5aA....
  • Sub-step 2: Select Investment Tranche: Decide on your risk appetite. Depositing into the junior tranche might require you to call a function like depositJunior(1000000000) where the value is in the token's smallest unit (e.g., 1,000 USDC = 1000000000 for 6 decimals).
  • Sub-step 3: Confirm Deposit and Receive Position Token: Execute the deposit. You will receive a receipt token (e.g., an ERC-20 like mUSDC-J) representing your share of the pool. Track its value relative to the underlying asset.

Tip: Always verify the Annual Percentage Yield (APY) for each tranche, which can range from 5% for senior to 20%+ for junior, but is highly variable based on pool performance.

3

Borrower Onboarding and Credit Analysis

The process for a whitelisted borrower to draw down a loan.

Detailed Instructions

For a borrower (typically an institution or DAO), accessing capital requires passing the protocol's off-chain credit assessment and on-chain whitelisting. This step is where the under-collateralization is formally enacted, based on trust and verified identity rather than locked crypto assets.

  • Sub-step 1: Submit KYC and Financials: Provide required documentation to the Pool Delegate or protocol's credit committee. This is an off-chain process establishing creditworthiness.
  • Sub-step 2: Receive Whitelisted Borrower Status: Upon approval, your wallet address (e.g., 0xBorrower123...) is added to the pool's whitelist via a governance transaction. You can verify this by checking the isBorrower mapping in the pool contract.
  • Sub-step 3: Draw Down the Loan: Call the drawdown function on the loan contract, specifying the amount. For example: ```code ILoanContract(0xLoan123).drawdown(500000000000000000000000); // Draws 500,000 USDC
code
The funds are transferred from the pool to your address, creating a debt obligation. > **Tip:** Borrowers must understand the **loan covenant** terms, including the **interest rate** (e.g., 10% fixed APR) and **repayment schedule**, which are enforced by the smart contract.
4

Monitoring and Liquidation Triggers

Ongoing oversight and the process for handling borrower default.

Detailed Instructions

The architecture must include robust monitoring oracles and automatic liquidation triggers to protect lenders. This step involves tracking the borrower's financial health and the protocol's overall health score, which can trigger recovery actions.

  • Sub-step 1: Track Payment Status: Monitor the borrower's wallet for scheduled interest payments. Missed payments are a primary default signal. You can set up a bot to listen for the Repayment event from the loan contract.
  • Sub-step 2: Assess Covenant Breaches: Oracles or keepers check if the borrower violates terms (e.g., their real-world assets drop below a threshold). A breach can be reported by calling a function like reportDefault(loanId).
  • Sub-step 3: Initiate Liquidation Process: Upon a verified default, the liquidation process begins. The first-loss capital (junior tranche) is used to cover initial losses. A keeper might execute:
code
IPool(0xPool456).triggerDefault(loanId);

This starts the waterfall, potentially involving legal recourse off-chain to recover funds from the borrower.

Tip: Liquidity providers should use dashboards that aggregate pool health metrics, such as Default Rate and Weighted Average Yield, to make informed decisions about reinvesting or exiting.

Protocol Model Comparison

Comparison of key features across under-collateralized lending protocol models.

FeatureCredit Delegation (Aave)Risk Tranches (TrueFi)Identity-Based (Goldfinch)

Primary Collateral Type

Delegated credit lines from over-collateralized positions

Junior tranche capital as first-loss protection

Off-chain borrower identity & financials

Default Risk Bearer

Delegating liquidity provider

Junior tranche token holders

Senior pool & backers via loss protection

Typical Loan Term

Open-ended / variable

Fixed-term (e.g., 90 days)

Fixed-term (e.g., 12-48 months)

Underwriting Method

Trust-based delegation between known parties

On-chain DAO vote & risk scoring

Off-chain SPV & borrower due diligence

Interest Rate Model

Variable, set by supply/demand on credit line

Fixed, set at loan origination

Fixed, set per borrower pool

Example TVL (approx.)

$150M in credit delegation

$400M in total value locked

$100M in active lending

Representative Asset

USDC delegated from aUSDC

TRUFi tokens representing tranche risk

FIDU tokens representing pool shares

Stakeholder Perspectives and Considerations

Accessing Capital with Less Collateral

Under-collateralized lending allows users to borrow more value than the assets they lock up, based on factors like creditworthiness or future cash flows. This is a paradigm shift from over-collateralized models used by protocols like MakerDAO.

Key Advantages

  • Increased Capital Efficiency: Borrowers can leverage their reputation or income streams to access larger loans without tying up excessive capital. For instance, a freelancer could use a verifiable income history from a platform like Utopia Labs to secure a loan.
  • Flexible Use Cases: Ideal for working capital, business expansion, or seizing time-sensitive investment opportunities that require immediate liquidity.
  • Credit-Based Terms: Protocols may offer lower interest rates or higher borrowing limits to users with strong on-chain history or off-chain credit scores, similar to how Goldfinch delegates assessment to "Backers."

A Practical Scenario

When using a protocol like Maple Finance, a decentralized business (a "Pool") might borrow significant capital against future revenue projections and a partial collateral deposit, enabling growth that would be impossible under traditional DeFi models requiring 150% collateralization.

Building a Risk Assessment Framework

Process overview for evaluating risks in under-collateralized lending protocols.

1

Define Protocol Parameters and Risk Factors

Identify and quantify the core variables that determine protocol risk.

Detailed Instructions

Begin by cataloging the protocol-specific parameters that directly influence risk. This includes the loan-to-value (LTV) ratio, liquidation thresholds, and the interest rate model. For each parameter, establish a baseline and a range of stress-test values. For instance, if a protocol uses a variable interest rate, you must model the rate function.

  • Sub-step 1: Extract on-chain parameters using the protocol's smart contracts. Query the main pool contract for key configuration values.
  • Sub-step 2: Model the interest rate curve. Determine if it's linear, kinked, or follows a complex formula like Jump Rate or White Paper model.
  • Sub-step 3: Identify oracle dependencies. Note the addresses of all price oracles used (e.g., Chainlink ETH/USD feed: 0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419) and their update frequency.

Tip: Use a block explorer or a library like ethers.js to read contract state. Documenting these parameters creates the foundation for all subsequent stress tests.

2

Analyze Collateral and Borrower Quality

Assess the assets accepted as collateral and the creditworthiness of borrowers.

Detailed Instructions

Under-collateralized lending relies heavily on borrower reputation and collateral asset volatility. This step involves creating a scoring system. For collateral, analyze the price history, liquidity depth on DEXs, and smart contract risks of the token. For borrowers, examine on-chain history, including wallet age, transaction volume, and debt repayment history from other protocols.

  • Sub-step 1: Score collateral assets. Use a 30-day volatility metric. For example, a stablecoin like USDC might score 1 (low risk), while a volatile altcoin might score 5 (high risk).
  • Sub-step 2: Develop a borrower health metric. Calculate a score based on factors like total borrowings vs. total deposits across DeFi (health_factor = total_collateral_value / total_borrowed_value).
  • Sub-step 3: Set risk tiers. Define thresholds for your scores (e.g., Green: health factor > 2.0, Yellow: 1.5-2.0, Red: < 1.5) to trigger different monitoring levels.

Tip: Leverage subgraph queries or APIs from platforms like DeFi Llama to gather historical price and protocol data efficiently.

3

Model Liquidation Mechanics and Stress Scenarios

Simulate the liquidation process under adverse market conditions.

Detailed Instructions

The liquidation engine is the primary risk mitigation tool. You must model its behavior precisely. This involves understanding the liquidation incentive (bonus for liquidators), the liquidation threshold, and the process's gas cost efficiency. Create simulations where collateral value drops rapidly to test if the system remains solvent.

  • Sub-step 1: Code a simple liquidation check. For a given position, verify if it's eligible for liquidation.
javascript
// Pseudo-code for liquidation check function isLiquidatable(collateralValue, borrowedValue, liquidationThreshold) { let collateralRatio = (collateralValue / borrowedValue) * 100; return collateralRatio < liquidationThreshold; // e.g., 85% }
  • Sub-step 2: Run price shock scenarios. Model a 24-hour price drop of 20%, 40%, and 60% for the collateral asset. Calculate the percentage of positions that become undercollateralized.
  • Sub-step 3: Assess liquidation capacity. Estimate the available liquidity in the system to absorb bad debt if liquidations fail, considering the protocol's insurance fund or shared loss mechanisms.

Tip: Factor in network congestion; a gas price spike to 200 gwei can make small liquidations unprofitable, causing delays.

4

Implement Continuous Monitoring and Alerting

Establish a system to track risk metrics in real-time and trigger alerts.

Detailed Instructions

A static assessment is insufficient; you need real-time monitoring. This step involves setting up data pipelines to track the key metrics defined earlier. The goal is to create an early warning system that flags deteriorating positions, oracle staleness, or parameter changes before they cause losses.

  • Sub-step 1: Set up indexers or subgraphs. Subscribe to events like Borrow, Repay, Liquidate, and PriceUpdate from the protocol's contracts.
  • Sub-step 2: Define alert thresholds. Program alerts for specific conditions, such as: health_factor < 1.1, oracle_last_update > 3600 seconds, or pool_utilization_rate > 90%.
  • Sub-step 3: Choose an alerting channel. Configure integrations to send notifications via Discord webhooks, Telegram bots, or email. For example, a Discord webhook URL would be specified in your monitoring script's configuration.

Tip: Use a service like The Graph for indexing and a lightweight serverless function (e.g., AWS Lambda) to evaluate conditions and dispatch alerts periodically, ensuring your framework is always active.

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