trader
businessperson who exchanges stocks, bonds and other such financial instruments
arbitrageur
person or firm that engages in arbitrage
stockbroker
professional who buys and sells shares and other securities for both retail and institutional clients
floor trader
member of a stock or commodities exchange who trades on the floor of that exchange
Rogue trader
employee authorized to make trades on behalf of their employer who makes unauthorized trades
stock trader
person or company involved in trading equity securities
day trader
trader who adheres to a trading style called day trading