Warren Buffett on portfolio concentration

We believe that a policy of portfolio concentration may well decrease risk if it raises, as it should, both the intensity with which an investor thinks about a business and the comfort-level he must feel with its economic characteristics before buying into it.

~ Warren Buffett

Warren Buffett on investment advice from Keynes

John Maynard Keynes essentially said, don't try and figure out what the market is doing.  Figure out a business you understand, and concentrate.

~ Warren Buffett

Philip Fisher on portfolio size

Usually, a very long list of securities is not a sign of the brilliant investor, but of one who is unsure of himself.

~ Philip Fisher, stock legend, "Five More Don'ts for Investors", Common Stocks and Uncommon Profits, 1958