Dear All,
I am currently working on an event-study related topic and stumbled accross a significance tests that requires to calculate the sample cross correlation (see Screenshot). My sample contains 50 companies but I actually don't have any idea how to calculate the average cross correlation for my sample. The xcorr function only works for two different variables if I am right but here I am looking for the correlation between all 50 companies. Anyone in here has a clue how to solve this issue?

Screenshot of the test statistic:
Array

Thanks a lot in advance!

Best regards
Raphael