Hello, everyone!

I am fairly new to Stata and I am trying to work out how to exclude some oberservations from my data set. My data set contains around 80000 observations of U.S. banks in quarterly date format between 2013 and 2015. The first quarter is the first of 2013 and the last the fourth of 2015. I want to exclude all banks that do not have observations for all the 12 quarters. I know that Stata can handle unbalanced data but I would still like to do it. I guess I do it with the drop command but I do not know how.

Many thanks in advance,
Marie