Some users borrow assets in the same currency as their collateral. For example, a user might lend USDC and then borrow USDC at a variable rate against it. Users might do this if they thought that the fixed rate they lent at would be higher than the variable borrow rate.
When a user's debt and collateral are in the same currency, the debt factor and collateral factor of that currency are irrelevant for calculating the users max LTV.
Max LTVs for single-currency portfolios only depend on the local-currency risk factors applied to the collateral and debt assets in the portfolio.
Example calculations
Here are some example max LTV calculations for single-currency portfolios.
Example 1: fUSDC collateral vs. prime USDC debt
Collateral: 2,000 USDC worth of fUSDC
Debt: 1,000 USDC of Prime USDC
Collateral value post-fUSDC haircut: 1,960
Prime USDC borrow buffer: 0
LTV = 1,000 / 2,000 = 0.5
Risk-adjusted loan value = 1,000 * (1 + 0) = 1,000
Risk-adjusted collateral value = 1,960
Risk-adjusted LTV = 1,000 / 1,960 = 0.51
Max LTV = 0.5 / 0.51 = 0.98
Example 2: nUSDC collateral vs. prime USDC debt
Collateral: 2,000 USDC worth of nUSDC
Debt: 1,000 USDC of Prime USDC
nUSDC haircut: 0.15
Prime USDC borrow buffer: 0
LTV = 1,000 / 2,000 = 0.5
Risk-adjusted loan value = 1,000 * (1 + 0) = 1,000
Risk-adjusted collateral value = 2,000 * (1 - 0.15) = 1,700
Risk-adjusted LTV = 1,000 / 1,700 = 0.5882
Max LTV = 0.5 / 0.5882 = 0.85
Example 3: nUSDC collateral vs. fUSDC debt
Collateral: 2,000 USDC worth of nUSDC
Debt: 1,000 USDC of fUSDC
nUSDC haircut: 0.15
Debt value post-fUSDC buffer: 1,020
LTV = 1,000 / 2,000 = 0.5
Risk-adjusted loan value = 1,020
Risk-adjusted collateral value = 2,000 * (1 - 0.15) = 1,700
Risk-adjusted LTV = 1,020 / 1,700 = 0.6
Max LTV = 0.5 / 0.6 = 0.8333
