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Fathom

# Fathom Active loans Methodology

## 1. Overview

The active loans metric measures the total outstanding loan amounts across all lending markets in the Fathom lending protocol. This metric tracks the cumulative value of variable-rate loans that borrowers have taken out but not yet repaid, providing insight into the protocol's lending activity and credit exposure. The calculation processes blockchain events to track loan originations and repayments, maintaining running balances of outstanding debt positions.

## 2. Data sources

The calculation relies on several key data sources:

- **XDC blockchain event logs**: Parsed `VToken_Mint_event` logs that record new variable-rate loan originations and `VToken_Burn_event` logs that record loan repayments
- **Lending market configuration**: Parsed `LendingPoolConfigurator_ReserveInitialized_event` logs that define the lending markets and associate underlying tokens with debt tokens
- **End-of-day token price feeds**: Daily price data for converting loan amounts to USD values
- **Token metadata**: Token decimals and symbol information for proper amount calculations and display formatting

## 3. Step-by-step calculation

### Component A: Lending market definitions
- **Purpose**: Establish the mapping between debt tokens and underlying assets in Fathom's lending markets
- **Logic**: Extract market configuration from `LendingPoolConfigurator_ReserveInitialized_event` logs on XDC chain, identifying the relationships between underlying tokens, aTokens (deposit receipts), and vTokens (variable debt tokens). Each market is associated with the Fathom Lending v3 protocol and linked to the main lending pool address.
- **Key fields**: Pool configurator address, underlying `asset` token address, `aToken` address, `vToken` address, and lending pool identification

### Component B: Variable debt token activity tracking
- **Purpose**: Capture all borrowing and repayment activity through debt token mint and burn events
- **Logic**: Process `VToken_Mint_event` logs to identify new loan originations, extracting the debt token address, borrower address, loan `value`, and interest rate `index`. Similarly, process `VToken_Burn_event` logs to track loan repayments with the same data fields. Both event types are timestamped and include transaction context for proper ordering.
- **Key fields**: Variable debt token address (`vtoken_address`), borrower address (`from_address`), loan amount (`value`), interest rate index, block timestamp

### Component C: Outstanding borrow calculations  
- **Purpose**: Calculate the net outstanding loan balance for each debt token over time
- **Logic**: Combine mint events (positive amounts representing new borrows) with burn events (negative amounts representing repayments) for each variable debt token. Group events by day and debt token, then apply a cumulative sum window function ordered by date to track the running balance of outstanding loans. This creates a time series of total outstanding debt for each lending market.
- **Key fields**: Daily timestamp, debt token address, daily net change amount, cumulative outstanding balance

### Component D: Active loans by market
- **Purpose**: Transform outstanding debt balances into the final active loans metric format
- **Logic**: Join outstanding borrow data with lending market definitions to associate debt positions with underlying token addresses and market metadata. For each day and lending market, select the latest calculated position using row numbering ordered by processing sequence. Apply decimal corrections to convert raw blockchain amounts to proper token units based on token metadata.
- **Key fields**: Underlying `token_address`, lending pool address, corrected loan `amount`, market name combining pool and token information

### Final aggregation
- **Combining components**: Sum active loan amounts across all lending markets, grouping by day, chain, product, and underlying token address to create daily totals per token
- **Currency conversion**: Convert corrected token amounts to USD using end-of-day price feeds matched to the underlying token addresses
- **Time aggregation**: Apply fill-forward logic to ensure continuous daily time series, carrying forward the last known active loan amount for any missing days
- **Final calculation**: The metric represents the total USD value of outstanding variable-rate loans across all Fathom lending markets, aggregated by day and available token, with proper decimal corrections and USD conversion applied

*This methodology was automatically generated by Token Terminal's methodology analyzer.*

Value of loans currently outstanding to borrowers.

Fathom

Active loans

Active loans

Competitive landscape