Rho Markets Contract Overview

Introduction

Rho Markets is a decentralized lending protocol that allows users to borrow and supply crypto assets. The core mechanisms include supply, borrowing, liquidation, and governance. Users earn interest by supplying assets or pay interest when borrowing assets.

Core Contracts

Comptroller

The Comptroller is the main management contract in Rho Markets, responsible for:
Managing the addition and removal of markets
Setting borrowing and liquidation parameters
Calculating user liquidity and health factor
Distributing RATE token rewards
- [WIP]

Global Factors

Global factors are common parameters that apply to the entire Rho Markets protocol. These are usually set at the governance level and affect all assets. The main global factors include:

Reserve Factor:
- Determines the portion of each interest payment that is reserved into the protocol’s reserves.
- For example, if the reserve factor is 10%, then 10% of each interest payment is reserved, and the remaining 90% is distributed to suppliers.
Close Factor:
- Determines the maximum portion of a borrower’s debt that can be repaid during liquidation.
- For example, if the close factor is 50%, then liquidators can repay up to 50% of the borrower’s debt.
Collateral Factor:
- Determines the proportion of an asset’s value that can be borrowed.
- For example, if the collateral factor is 75%, an asset worth $100 can be used to borrow up to $75 of other assets.
Liquidation Incentive:
- Determines the reward given to liquidators during liquidation.
- For example, if a token has a liquidation incentive of 110%, liquidators can buy collateral at a 10% discount during liquidation.

Factor Type	Reserve Factor	Close Factor	Collateral Factor	Liquidation Incentive
Global Factor	0.02	0.02	1.5	1.1

Precision of FactorsIn smart contract programming, using fixed precision is a common practice to ensure the accuracy of numerical operations.All factor values are specified with a precision of 1e18. This means that the factor values are multiplied by 1e18 to avoid precision issues that arise from floating-point arithmetic in smart contracts. For example, if the reserve factor is 10%, the value set in the contract would be 0.1 * 1e18 = 1e17

RToken

RToken contracts represent the lending markets for each asset, such as rETH, rUSDC, etc. Key functions include:

mint: Supply underlying assets to the protocol and receive rTokens
redeem: Redeem underlying assets
borrow: Borrow underlying assets
repayBorrow: Repay borrowed assets

Asset

Per-Token Factors

Each token has its own unique factor settings, which determine the behavior and risk parameters of that specific token within the protocol.

Reserve Factor

Each token can have its own reserve factor, determining the portion of its interest payments that go into the reserves.

Collateral Factor

Determines the proportion of that specific token's value that can be borrowed.
High-risk assets typically have lower collateral factors, while low-risk assets have higher collateral factors.

Seize Share:

Determines the portion of seized collateral that is distributed to liquidators during the liquidation process.
For example, if the seize share is 2.8%, it means that liquidators receive 2.8% of the seized collateral as a reward.

Borrow And Supply Caps

Borrow and supply caps are limits set on the amount of a specific asset that can be borrowed or supplied within the protocol. These caps help manage risk by preventing excessive borrowing or supplying of a particular asset, which can lead to liquidity or volatility issues.

Assets	Reserve Factor	Collateral Factor	Supply Caps	Borrow Caps	Seize Share
rETH	0.075	0.7	4500e18	3500e18	0.028
rSTONE	0.075	0.7	5000e18	100e18	0.028
rUSDC	0.075	0.7	10000000e6	5000000e6	0.028
rUSDT	0.075	0.7	10000000e6	5000000e6	0.028
rwstETH	0.075	0.7	4000e18	2000e18	0.028
rsolvBTC	0.075	0.7	300e18	0	0.028
rweETH	0.075	0.7	1000e18	300e18	0.028
rwrsETH	0.075	0.7	1500e18	100e18	0.028
rUSDe	0.075	0.7	10000000e18	100e18	0.028

InterestRateModel

The InterestRateModel contract defines the interest rate model for each market. Rates adjust dynamically based on the utilization rate of the market to balance supply and demand.Note: For deployments on the Scroll network, the blocksPerYear parameter should be adjusted to account for Scroll's faster block times, which are four times faster than Ethereum. Therefore, the blocksPerYear should be set to 9556363

JumpRateModel

The JumpRateModel is a specific type of interest rate model used in some Rho markets. It features a "jump" in the interest rate at a certain utilization point, which helps maintain liquidity. This model has three key parameters:

Base Rate: The interest rate when the utilization is 0%.
Multiplier: Determines the increase in the interest rate as utilization increases.
Jump Multiplier: A higher rate that applies once utilization surpasses a certain threshold, incentivizing more liquidity supply.
Kink: The utilization point at which the jump multiplier is applied

Assets	BaseRatePerYear	MultiplierPerYear	JumpMultiplierPerYear	kink	address
rETH	0.02	0.02	1.5	0.9	0x246bFFD3c58688EAA915de0A59d0c04424f9aafC
rSTONE	0.02	0.03	3.5	0.7	0x98e90a584B99AC437D8535E3B265c54E6DD2eCcb
rUSDC	0.02	0.03	1.5	0.9	0xfb2cb244c950681ED8CF8AdB2ddF69423486Bb98
rUSDT	0.02	0.03	1.5	0.9	0xfb2cb244c950681ED8CF8AdB2ddF69423486Bb98
rwstETH	0.02	0.03	3.5	0.7	0xfb2cb244c950681ED8CF8AdB2ddF69423486Bb98
rsolvBTC	0.02	0.03	3.5	0.7	0x98e90a584B99AC437D8535E3B265c54E6DD2eCcb
rweETH	0.02	0.03	3.5	0.7	0x98e90a584B99AC437D8535E3B265c54E6DD2eCcb
rwrsETH	0.02	0.03	1.5	0.9	0x98e90a584B99AC437D8535E3B265c54E6DD2eCcb
rUSDe	0.02	0.03	3.5	0.7	0x98e90a584B99AC437D8535E3B265c54E6DD2eCcb

PriceOracle

The PriceOracle contract provides price information for market assets, used to calculate borrowing and liquidation eligibility.

getGracePeriodTime: Returns the grace period time set for price feeds.
getFreshCheck: Returns the threshold time for considering a price feed as “fresh”.
getSequencerUptimeFeed: Returns the address of the sequencer uptime feed used to check if the sequencer is up
getChainlinkPriceFeed: Returns the Chainlink price feed address for a given RToken
getChainlinkPrice: Fetches the latest Chainlink price for a given RToken
getPrice(RToken rToken): Returns the current price for the specified RToken using the highest priority oracle
getUnderlyingPrice: Returns the underlying asset’s price for the specified RToken