It all depends on where the report gets its data from. A report can only get data from one query, however one query can get data from multiple tables.
Not knowing how your report is formatted, it's hard to give an answer regarding sorting by company.
If your query already returns all the necessary records and all you need to do it sort by company, you can either make a new report based on your existing query (the wizard can help) or go into the Sorting & Grouping section of your existing report and add a grouping by company.