This Bank of America chart from July 2012 seen here shows bank ownership of the equity markets at 32% in Q1 2012, a stunning number rivalling the household sector's share of 37%. In 1950 households (an elastic category including much more than simply retail investors) held roughly 90% of the market in their hands (admittedly far fewer retail investors than today, but that's another story).
So you've got to ask yourself why ultra cheap loans to banks by the Federal Reserve have gone into markets in such spectacular fashion? To help them recapitalize after the housing implosion, that's why. Banks can't make money the old fashioned way anymore because the owners' equity of household real estate of consumers is down to about 45% (it had sunk as low as 39% in 2010 and 2011), a decline of over 45% since 1950. Think cash-out-refis at artificially low interest rates and HELOCS and the housing market collapse. The banks are left holding the bag, or the Feds are, on 5 million repossessed properties in the last seven years, leaving a huge capital hole in their off-balance-sheet balance sheets. Having plundered John Q. Public by selling him the rope he hung himself with (HELOC reform 1986 Tax Reform, Taxpayer Relief Act of 1997 2-Year Rule on Sale of Principal Residence, Repeal of Glass-Steagall 1999), the government-banking cartel has had to look elsewhere for profits. They're finding them.
Care to buy stocks?