Or is it? We are told never put your eggs in one basket. Diversify. etc... It's become such a cliche. Do you ever question it? but I knew a trader who invested in one stock at a time and made millions. (he's drawdowns wre enormous but I guess if you make $2millin and give back $1million you are happy) If you wait for almost sure things and do not trade any old stock IS investing in one stock at a time a sure way to lose it all or make a fortune?