90%的交易是机构买卖。copy 书上写得

 Ninety percent or more of all trading in large markets is done by institutions, which means that the market is simply a collection of institutions.

The small-volume trades made by individuals can only take place if an institution is willing to take the same trade. If you want to buy at a certain price, the market will not get to that price unless one or more institutions also want to buy at that price.