Definition of 'Open Position'
In investing, any trade that has been established, or entered, that has yet to be closed with an opposing trade. An open position can exist following a buy (long) position, or a sell (short) position. In either case, the position will remain open until an opposing trade has taken place.
Investopedia explains 'Open Position'
For example, an investor who owns 500 shares of a certain stock is said to have an open position in that stock. When the investor sells those 500 shares, the position will be closed.
Buy-and-hold investors generally have one or more open positions at any given time. Short-term traders may execute "round-trip" trades; a position is opened and closed within a relatively short period of time. Day traders and scalpers may even open and close a position within a few seconds, trying the catch very small, but frequent, price movements throughout the day.