# Fathom Lending Total value locked Methodology

## 1. Overview

Total value locked (TVL) for Fathom Lending measures the total value of all assets deposited into the protocol's lending markets. This metric includes both the idle liquidity available for borrowing and the value of active loans currently held by borrowers. TVL serves as a primary indicator of the protocol's capacity to facilitate lending and the overall demand for its credit services on the XDC network.

## 2. Data sources

- **Blockchain events**: `ReserveInitialized` events from `LendingPoolConfigurator` contracts, `Mint` and `Burn` events from `VToken` contracts, and ERC-20 token transfers, covering XDC
- **External data**: End-of-day price feeds for the underlying assets

## 3. Step-by-step calculation

### Component A: Market identification

- **Purpose**: Identify and map the smart contracts associated with each Fathom Lending market
- **Logic**: Markets are identified by parsing `ReserveInitialized` events from `LendingPoolConfigurator` contracts. This process establishes the mapping between underlying assets and their corresponding interest-bearing aToken contracts and debt-tracking `VToken` contracts.
- **Key fields**: `underlying_token_address`, `atoken_address`, `vtoken_address`

### Component B: Idle liquidity tracking

- **Purpose**: Calculate the value of deposited assets remaining in the lending pools
- **Logic**: Net deposits are tracked by monitoring ERC-20 token transfers to and from the identified aToken contract addresses. Transfers to the aToken address are treated as inflows, while transfers from the aToken address are treated as outflows. Daily changes are aggregated and summed chronologically to determine the total cumulative idle balance per asset.
- **Key fields**: `amount`, `to_address`, `from_address`, `token_address`

### Component C: Active loan tracking

- **Purpose**: Calculate the value of assets currently borrowed from the protocol
- **Logic**: Outstanding variable debt is tracked by parsing `Mint` and `Burn` events from `VToken` contracts. `Mint` events indicate the initiation or increase of a loan, while `Burn` events indicate repayments. These events are aggregated daily and summed cumulatively to calculate the total outstanding borrow balance for each market.
- **Key fields**: `value` (loan amount), `vtoken_address`

### Component D: USD conversion and final aggregation

- **Purpose**: Normalize values and aggregate the components into a single USD-denominated metric
- **Logic**: Idle balances and active loan amounts are normalized by their respective decimal precision. The values are multiplied by end-of-day price feeds for the underlying assets to determine the USD value. Total value locked is calculated as the sum of total idle liquidity and total active loans. Missing daily data points are filled forward using the last known balance to maintain a continuous time series.
- **Key fields**: `price_usd`, `decimals`, `tvl` (sum of idle and borrowed components)

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

Total value locked (TVL)

Total value locked (TVL) — value deposited into the project's applications.

Total value locked

Lending