Bank size distributions concentrate in a few large banks – the big “grains.” This fact means idiosyncratic shocks at the bank level do not cancel out, thus affecting the business cycle. Here, we present evidence of granularity in the banking market using Brazilian data. We examine the explanatory power of the granular banking residual of the five largest banks on quarterly GDP changes from 2010 to 2019. We conservatively find that shocks to revenues of these top five banks explain nearly one-fifth of GDP fluctuations.