Trader is a notion of polysemantic meaning. It’s basic meaning is a person who carries out exchange of something: e.g., money and goods, etc. Yet, the word was primarily used with  shade of offensive meaning in order to denote a person who speculates something with only aim – getting income, possibly – with breaking the law or not keeping ethics or rules of conduct.  Trader is a physical individual or legal body. Normally individual trader with his own investments. A trading company (or traders of a trading company) use the investments of other people to trade.