There are four audit companies -- PwC, Deloitte, EY, and KPMG -- that together audit 99% of companies in the FTSE 100. If you don&#x27;t hire them, you get looked at funny.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Big_Four_%28audit_firms%29" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Big_Four_%28audit_firms%29</a>