Coslend
Search
K
Comment on page

# Interest Rate Model

## Borrow Interest Rate Model

Coslend use Jump model, the interest rate curve is split in two parts around an optimal utilisation rate
$U_{optimal}$
.
The borrow interest rate
$R_t$
follows the model:
$if \hspace{1mm} U < U_{optimal}: \hspace{1cm} R_t = R_0 + \frac{U_t}{U_{optimal}} R_{slope1}$
$if \hspace{1mm} U \geq U_{optimal}: \hspace{1cm} R_t = R_0 + R_{slope1} + \frac{U_t-U_{optimal}}{1-U_{optimal}}R_{slope2}$
Before
$U_{optimal}$
the slope is small, after it starts rising sharply.

## Supply Interest Rate

The borrow interest rates paid are distributed as yield for cToken holders who have supplied in the protocol, excluding a share of yields sent to the ecosystem reserve defined by the reserve factor. This interest rate is paid on the capital that is lent out then shared among all the liquidity providers.
The supply interest rate,
$S_t = U_t *R_t*(1-Reserve Factor)$
• $U_t$
, the utilization ratio
• $R_t$
, the borrow rate
• $Reserve Factor$
, the reserve factor

## APR & APY Calculation

### APR

borrowRateAPR = borrowRatePerSec * secsPerYear* 100 / 1e18
supplyRateAPR = supplyRatePerSec * secsPerYear* 100 / 1e18

### APY

borrowRateAPY = ((1 + borrowRatePerBlock/1e18) ** secsPerYear - 1) * 100
supplyRateAPY = ((1 + supplyRatePerBlock /1e18) ** secsPerYear - 1) * 100
**SecsPerYear = 60*60*24*365 = 31,536,000

## Interest Rate Model Parameters & Curves

### Stablecoin

 Asset ​$U_{optimal}$​ Base Slope 1 Slope 2 USDC 80% 0% 4% 21.8% USDT 80% 0% 4% 21.8% FRAX 80% 0% 4% 21.8% DAI 80% 0% 4% 21.8%

### Major

 Asset ​$U_{optimal}$​ Base Slope 1 Slope 2 WETH 80% 2% 18% 20% WBTC 80% 2% 18 20%

### Eco

 Asset ​$U_{optimal}$​ Base Slope 1 Slope 2 EVMOS 50% 2% 10% 150%
Asset
Token
cToken
Interest Rate Model
USDC
0xc20712e5D23E8b2F6b0fb450238819AC54E9b752
0x94B56C71e2243bC1E40Ab9bA28C890459e4Cd0B5
USDT
0x7FF4a56B32ee13D7D4D405887E0eA37d61Ed919e
0x02684f6C0be4EdBeD82019C3C159a36CCFd7E7a3
0x94B56C71e2243bC1E40Ab9bA28C890459e4Cd0B5
FRAX
0xE03494D0033687543a80c9B1ca7D6237F2EA8BD8
0xd58e11AA32878617248Eb956891cB22438D4A0FD
0x94B56C71e2243bC1E40Ab9bA28C890459e4Cd0B5
WETH
0x5842C5532b61aCF3227679a8b1BD0242a41752f2
0x16B77c79f7F03cEc6536dBceAf825DB60B0Dd675
0x49881448d25205aB9853b05A110b6cEd464C3e4B
WBTC
0xF80699Dc594e00aE7bA200c7533a07C1604A106D
-
0x49881448d25205aB9853b05A110b6cEd464C3e4B
EVMOS
0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
-