Time Horizons Planning horizon The total length of time for which one plans Decision horizon The length of time between decisions to revise a portfolio Trading horizon The shortest possible time interval over which investors may revise their portfolios THE COURSE OF FINANCE 2017 SPRING SJTU 10Time Horizons  Planning horizon The total length of time for which one plans  Decision horizon The length of time between decisions to revise a portfolio  Trading horizon The shortest possible time interval over which investors may revise their portfolios THE COURSE OF FINANCE 2017 SPRING SJTU 10