I assume you're talking about stock brokers? I think it might depend on the instruments being offered.
I was a money broker for a good many years and there's certainly no qualifications needed there besides being fast and being able to shout louder than anyone else in the room

. I also worked at a firm which acted as a "broker" for the Japanese stock and bond markets for which there was no special qualifications necessary.
The only thing I can think of might be that certain US financial instruments traded over the counter may require regulation from the National Association of Securities Dealers (NASD), although I am not absolutely certain.
Certainly any broker who takes positions in their own name should be recognised by the Eidgenössiche Bankenkommision as either a bank or Effektenhändler.