Professional Day Trading

professional
a person engaged in one of the learned professions
an athlete who plays for pay
engaged in a profession or engaging in as a profession or means of livelihood; "the professional man or woman possesses distinctive qualifications"; "began her professional career after the Olympics"; "professional theater"; "professional football"; "a professional cook"; "professional actors
Having or showing the skill appropriate to a professional person; competent or skillful
Of, relating to, or connected with a profession
(of a person) Engaged in a specified activity as one's main paid occupation rather than as a pastime

day trading
(Day traders) come to market each day flat (no position) and leave the day flat. Their behavior is very short-term and often emotional.
Day trading refers to the practice of buying and selling financial instruments within the same trading day such that all positions are usually closed before the market close for the trading day. Traders that participate in day trading are called active traders or day traders.
(Day traders) hold stocks for minutes to hours making numerous trades each day usually with a cursory understanding of the companies they trade.  These investors rely on timing and minimize risk by buying and then immediately selling.
The buying and selling of securities on the same day, often online, on the basis of small, short-term price fluctuations