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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
UoptimalU_{optimal}
.
The borrow interest rate
RtR_t
follows the model:
ifU<Uoptimal:Rt=R0+UtUoptimalRslope1if \hspace{1mm} U < U_{optimal}: \hspace{1cm} R_t = R_0 + \frac{U_t}{U_{optimal}} R_{slope1}
ifUUoptimal:Rt=R0+Rslope1+UtUoptimal1UoptimalRslope2if \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
UoptimalU_{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,
St=UtRt(1ReserveFactor)S_t = U_t *R_t*(1-Reserve Factor)
  • UtU_t
    , the utilization ratio
  • RtR_t
    , the borrow rate
  • ReserveFactorReserve 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
UoptimalU_{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
UoptimalU_{optimal}
Base
Slope 1
Slope 2
WETH
80%
2%
18%
20%
WBTC
80%
2%
18
20%

Eco

Asset
UoptimalU_{optimal}
Base
Slope 1
Slope 2
EVMOS
50%
2%
10%
150%
Asset
Token
cToken
Interest Rate Model
USDC
0x51e44FfaD5C2B122C8b635671FCC8139dc636E82
0xc20712e5D23E8b2F6b0fb450238819AC54E9b752
0x94B56C71e2243bC1E40Ab9bA28C890459e4Cd0B5
USDT
0x7FF4a56B32ee13D7D4D405887E0eA37d61Ed919e
0x02684f6C0be4EdBeD82019C3C159a36CCFd7E7a3
0x94B56C71e2243bC1E40Ab9bA28C890459e4Cd0B5
FRAX
0xE03494D0033687543a80c9B1ca7D6237F2EA8BD8
0xd58e11AA32878617248Eb956891cB22438D4A0FD
0x94B56C71e2243bC1E40Ab9bA28C890459e4Cd0B5
WETH
0x5842C5532b61aCF3227679a8b1BD0242a41752f2
0x16B77c79f7F03cEc6536dBceAf825DB60B0Dd675
0x49881448d25205aB9853b05A110b6cEd464C3e4B
WBTC
0xF80699Dc594e00aE7bA200c7533a07C1604A106D
-
0x49881448d25205aB9853b05A110b6cEd464C3e4B
EVMOS
0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
-
0x8bAd570e9AB4e90407e46a05aCEF2DeD5d8d5148
OSMO
0xFA3C22C069B9556A4B2f7EcE1Ee3B467909f4864
-
0x8bAd570e9AB4e90407e46a05aCEF2DeD5d8d5148
ATOM
-
0x8bAd570e9AB4e90407e46a05aCEF2DeD5d8d5148