An intelligent short term stock trading fuzzy system for assisting investors in portfolio management

• The proposed short-term fuzzy system uses a set of appropriate technical indicators.
• The returns of the proposed system are higher than those of the B&H strategy.
• The proposed system avoids big losses during bear markets.
• During bull markets the system produces lower returns than the B&H strategy.
• Transaction costs significantly affect the performance of the proposed system.

Financial markets are complex systems influenced by many interrelated economic, political and psychological factors and characterised by inherent nonlinearities. Recently, there have been many efforts towards stock market prediction, applying various fuzzy logic techniques and using technical analysis methods.This paper presents a short term trading fuzzy system using a novel trading strategy and an “amalgam” between altered commonly used technical indicators and rarely used ones, in order to assist investors in their portfolio management. The sample consists of daily data from the general index of the Athens Stock Exchange over a period of more than 15 years (15/11/1996 to 5/6/2012), which was also divided into distinctive groups of bull and bear market periods.The results suggest that, with or without taking into consideration transaction costs, the return of the proposed fuzzy model is superior to the returns of the buy and hold strategy. Τhe proposed system can be characterised as conservative, since it produces smaller losses during bear market periods and smaller gains during bull market periods compared with the buy and hold strategy.