This isn't news to those of us who have been investing/trading in common stocks for some time.

Consider the old Value Line publication of stock research. VL's flagship publication would list only about 1700 of over 5500 common stocks traded.

Or, we could consider some of the rules used by many mutual fund companies as criteria for inclusion in one of their funds: A share price of at least $10 and a volume of 250K shares (on average). Right there, you've selected a much smaller universe of stocks from which to choose.

The common stocks of small, under-capitalized, over-leveraged companies are a lottery ticket. Most don't pay off.