There are many ways to skin a cat. Investment styles and philosophies abound, but the last thing you want is to behave differently from the theory you adhere to. Here are some investment theories and their corresponding investment behaviour.
Theory: Stock prices are totally efficient and investors can only manage taxes and trading costs
Investment behaviour: Buy an index fund and avoid trading
Semi-strong Efficient Market
Theory: Stocks are fairly priced until news arrives
Investment behaviour: Trade on news flow
Weak Efficient Market
Theory: Less structured news is not properly reflected in prices
Investment behaviour: Read trade rags, do channel checks and gossip with competitors, customers and suppliers
Theory: For short periods, stocks will keep moving in one direction
Investment behaviour: Buy stocks whose prices have risen at the fastest rate
Valuation relative to history
Theory : Stocks prices move around fair value, which is a static function of EV/EBITDA
Investment behaviour: Buy stocks at the low end of their historic EV/EBITDA band.
Theory: Stock prices move irregularly around present value, which is the sum of shifting expectations about the future
Investment behaviour: Buy stocks that are priced far below their value using assumptions you believe
Besides making sure that your investment behaviour is consistent with your investment philosophy, it is also important to keep an open mind and consider the alternatives, why they may or may not work and why they may or may not be a better fit for you.