Time Series Analysis for multiple companies at the same time range? I have sales data of 100 different companies from 2016 to 2020 (monthly data).
These companies are from different sectors (SAAS, Ecomm, Service provider, etc)
I am working on an exercise to understand if companies from a sector is following the same seasonality on the monthly sales data.
The approach I am taking is analyzing one company at a time and checking the seasonality and taking another company and so on, what approach I can take to compare all companies from a sector to check if they are following same pattern or not?

If you already have some domain knowledge what are the reasonable seasons for causing the sales change, you can engineer this into features:
company.   SeasonX.  SeasonY.  SeasonZ etc
 A          120%.      150%.
 B.         150%.      120.

The percentage indicates the changes in sales compared to the previous season. Then you can apply clustering to the data and extract patterns which companies are similar in terms of their seasonality, and visualise this in PCA.
