Basis is a multiplier used to calculate the total interest paid or received in a defined time period. It is typically used in accounting and valuation for bonds, swaps, dividends, project finance, and other investments with periodic cash flows. Basis is also known as the "day count convention" because it defines how days in a year are treated for calculation purposes in different parts of the world.

Performance
Used for equity swaps, the payment is calculated as change in price times the notional. For example, assume the notional of the leg is 10000 shares (units) of stock X and resets monthly. If the share price at the beginning of the period was 20 and the ending price is 30, the payment is calculated as (30-20) * 10000 = 100000.