Complex sentence: Traders are either professionals working in a financial institution or a corporation, or casual investors or speculators in financial instruments traded in the stock markets, derivatives markets and commodity markets, comprising the stock exchanges, derivatives exchanges and the commodities exchanges.
Split into simpler sentences: Traders are either professionals working in a financial institution or a corporation, or casual individual investors or speculators. They buy and sell financial instruments traded in the stock markets, derivatives markets and commodity markets, comprising the stock exchanges, derivatives exchanges and the commodities exchanges.