So whats a trader with a huge chunk of stock to do? Big institutions — mutual, pension and endowment funds — have come to believe that hedge funds and investment banks are using the information in the orders to make money for themselves. Extraordinarily sophisticated computer programs can exploit the smallest transactions. Exchanges are aware of this, but can do little to stop it.
A hedge fund or a bank might trade on its own account before executing a clients order. In response, investors are splitting deals into tiny pieces. An "iceberg" offer of a few hundred shares is floated to see if demand or supply can be teased out for a bigger transaction.
Check out an article detailing how traders are hiding their large orders, published by The Economist, by clicking here.