The prime money market is Notional’s variable rate lending and borrowing market. The prime money market is similar to other money markets in DeFi like Aave or Compound. Variable rate lenders deposit funds into a pool, and over-collateralized borrowers can borrow from that pool and pay interest to the lenders.
The interest rate that the borrowers pay and the lenders earn is based on the pool's utilization. The prime money market uses a unique double-kink interest rate model to optimize for capital efficiency and predictability in borrow rates.

Prime Cash

When users deposit into the prime cash money market, they get prime cash in return. Prime cash is an ERC20 token that represents a lending position in the prime money market. There is a different Prime Cash token for each currency - for example Prime USDC, Prime DAI, and Prime ETH.
Prime Cash values always increase and Prime Cash is always redeemable for the underlying unless the prime money market is at 100% utilization.

Prime Cash Debt

Prime Cash Debt represents a variable rate debt position. For example, a USDC borrower would have Prime USDC Debt.
Prime Cash Debt increases based on the current variable borrow rate for borrowers in that currency.