I see people reference that the trading volume actually indicates twice the actual volume of shares trading hands as I assume they are counting the MM buying the shares from someone, and then the MM selling the shares to someone else.  That makes sense to me, but I've never seen this explained officially anywhere othere than in posts on message boards.  Considering financial websites seem to report the same volumes each day, I have always assumed that the volume equals the total shares transacted per day, MINUS the market maker.  Can anyone give me a link that explains this more celarly. Thanks.