How much concentration does a good trader make per trade? 10%? 20%? How concentrated or diversified should a portfolio be? There are arguments that concentration pays off with higher percentages, and diversification ends up being diworsification, but I've been thinking about a few money managers and traders that have gone the opposite route of concentration: Rennaissance Tech, Peter Lynch, Graves, and a few others. They've done very well taking very small positions, but owning lots of stocks. RT says they are like the Walmart of equities. I have a new strategy that I'm excited about that utilizes heavy diversification, but concentrates into the best performing equities. This would limit my volatility and exposure to any one company blowing up. And to protect against large blowups like the past year and in 2000, I just look for asset bubbles and use simple timing strategies. Anyone have any opinions on this?