Dear Stata Users,

Can you please help to construct a pre-event window of 23 days (including event date). I have this data (permno - firm):


Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input double permno long date
10031 10350
10031 10393
end
format %td date
I use this code to generate pre-event window:

Code:
expand 23
sort permno date
by permno date: gen byte t = _n
by permno date: gen int even_period = date + t - 23
format even_period %td
But this generates calendar dates and what I want is Business days (like 23 pre-event business days). Can you please guide me on the way I can generate a pre-event window based on business (rather than) calendar days?