what is a commission.
A commission is a fee paid to a third party in exchange for assistance in completing a financial transaction. A commission may either be a percentage of the value of the transaction, or a flat fee.In financial markets, a commission is commonly associated with stock transactions.tock and foreign exchange brokers may offer so-called zero commission trading. This may be a false economy for thrifty traders; instead of making money on a commission, such brokers make their money by either widening the spread or selling the right to execute the order to a market maker who can widen the spread.