As a Brazilian, I can add somethign here. This kind of floating rate contract (it is used in CDs, Swaps, Corporate Bonds, ...) was created several years ago when the Brazilian economic environment was very different: - High inflation rates and, even worst, inflation rate growing in a fast pace - due to lack of confidence everything everyone wanted to keep floaters and/or short term products. - Several Government economic plans and monetary shocks trying to control inflation - To reduce the reset risk, people started to use daily resets (CDI, the interbank overnight benchmark). Once the level of one day interest rate could change wildly, people started to change the way the spread over the rate is specified. Instead of CDI+Spread, the economic agents started working with % CDI.Even fund managers used % CDI as benchmark to calculate performance fees.There two, not excluding, ways to face this: - It doesn't make sense anymore and the market is very slowly moving away from % CDI (at first) and daily resets in general. But it will take several years to change the culture. - For someone that wants to trade in Brazil, not handling CDI is like not being to trade efficiently (or not being able to trade at all). For IR Swaps, it is much easier and cheaper to get counter parties when CDI is one of the legs. It is part of the game.