Trading profitably is usually easy for portfolio managers and most professional traders.
First, a trader should have access to a good advisory which forecasts the direction of each issue in the trader's portfolio. Take the profit and enter a new position based on the advisory that is proving itself with a high forecasting accuracy. The price of a stock usually rises to an overvalued level, then falls to an undervalued level. This is necessary in rapidly-changing financial markets. A forecasting system is used to create a trading system.