Only a small percentage of TWTR shares were up for sale in the IPO--there are 544.70M total shares and just 70M were part of the IPO (a little less than 13%). Unless I missed something the shares sold in the IPO were issued, so for example if you were a VC with a million shares of TWTR you would still have a million shares of TWTR (now valued at $45M). The money from the sale will go to Twitter, not an investor. Twitter did "leave money on the table", but their #1 goal was not to pull a Facebook and have the IPO be DOA.